Manual Transmission Oil Thoughts
04-29-2017, 01:41 PM
#34
Technical Guru
Rennlist Member
Rennlist Member
Here are the data sheets for the 2 Mobil Gear oils and Shell's offering that meet Porsche's performance standard as well Mobil One's standard OTC GL-5 offering;
Mobilube PTX 75w90 - OE fill, works great with LSD, especially good in colder weather, smoothest shifts with OE synchronizers. $39USD/liter
Mobilube Delvac SHC 75w90 Porsche Motorsports factory fill -
owners with daily driver Porsches tend to try once and then go back to something else. Plus absolutely horrible in cold weather. $42USD/gal
Shell Spirax S5 ATE 75w90 - Also OE fill
Mobilube LS 75w90 - OTC at most retailers, cheapest, designed for LSD, shifting is not as smooth as PTX/SHC. $13USD/qt
Mobilube PTX 75w90 - OE fill, works great with LSD, especially good in colder weather, smoothest shifts with OE synchronizers. $39USD/liter
Mobilube Delvac SHC 75w90 Porsche Motorsports factory fill -
owners with daily driver Porsches tend to try once and then go back to something else. Plus absolutely horrible in cold weather. $42USD/gal
Shell Spirax S5 ATE 75w90 - Also OE fill
Mobilube LS 75w90 - OTC at most retailers, cheapest, designed for LSD, shifting is not as smooth as PTX/SHC. $13USD/qt
05-01-2017, 12:31 PM
#35
Other than limited slip differentials, what are the negatives of using the standard weight 75W90 GL5 oil in either of the locations? Will I slowly destroy my transaxle by using Fuchs Titan Syntopoid or any other gear oil, or is it just a harder shifting problem?
John
John
05-01-2017, 12:35 PM
#36
(I'm reposting this from a post I made at 6speed a couple months ago. I tend to agree with those that prefer to use oem for this particular application)
I know many are having excellent results with various gear oils like Delvac, Red Line, etc..so I'm not trying to change anyones mind Just going to share the info I found. I have heard it mentioned a few times from folks running gear oils other than the Porsche approved ones that they have to be a little careful shifting when cold and then once warmed up all is great.
I spent some hours doing research on this recently since I'm getting ready to do my trans & diff fluids. There are only 2 "approved" gear oils by Porsche and they are:
1) Mobilube PTX
2) Shell Spirax S5 ATE (formerly known as Shell Transaxle)
As far as I know these are the only 2. There is no approved list with a bunch of different options, just these two.
I am not a lubricant engineer!!! just looking at the numbers to see if there are any consistent differences between the two approved Porsche fluids and all the others.
If you take a look below you will see that the approved fluids (Mobilube PTX and Spirax S5 ATE) both have almost identical numbers BUT the other 3 as well as just about all the other 75/90's out there have HIGHER Kinematic Viscosity (cSt) numbers AND LOWER Viscosity Index numbers. Could these differences be why some folks running the non-approved gear oils have to be a little more careful when cold? Good question!!!
The only gear oil I found specs on that seems to have really close properties to the Approved Mobilube & Shell Spirax is the Liqui-Moly 2048...
Mobil MOBILUBE PTX 75W-90 (Porsche approved)
Viscosity
cSt @ 40º C 77.6
cSt @ 100ºC 14.5
Viscosity Index 195
Flash Point, ºC 226
Pour Point, ºC -60
Density kg/m3 849
Shell Spirax S5 ATE 75W-90 (Porsche approved)
SAE J 306 75W-90 SAE Viscosity Grade
cSt @40 81
cSt @100 14.9
Viscosity Index 194
ISO 9262 35000 Dynamic Viscosity mPa s
0 3 ISO 12185 879 Density @15 C kg/m
0 ISO 2592 205 Flash Point (COC) C
Mobil Delvac 1 Gear Oil 75W-90
SAE Grade 75W-90
Viscosity, ASTM D 445
cSt @ 40ºC 120
cSt @ 100ºC 15.9
Viscosity Index 140
Pour Point, ºC, ASTM D 97 -48
Flash Point, ºC, ASTM D 92 205
Density @ 15ºC kg/l, ASTM D 4052 0.86
Redline 75W90 NS GL-5 Gear Oil
Vis @ 40°C, cSt 94.5
Vis @ 100°C, cSt 15.6
Viscosity Index 176
Pour Point, °C -45
Pour Point, °F -49
Brookfield Viscosity @ -40°C, Poise 400 @-40°C
**Liqui Moly 2048 ** (Very similar numbers to Porsche Approved)
Vis @ 40°C, cSt 80.9
Vis @ 100°C, cSt 14.3
Viscosity Index 184
Flash Point, °C 190
Pour Point, °C -60
Density kg/m3 855
I know many are having excellent results with various gear oils like Delvac, Red Line, etc..so I'm not trying to change anyones mind Just going to share the info I found. I have heard it mentioned a few times from folks running gear oils other than the Porsche approved ones that they have to be a little careful shifting when cold and then once warmed up all is great.
I spent some hours doing research on this recently since I'm getting ready to do my trans & diff fluids. There are only 2 "approved" gear oils by Porsche and they are:
1) Mobilube PTX
2) Shell Spirax S5 ATE (formerly known as Shell Transaxle)
As far as I know these are the only 2. There is no approved list with a bunch of different options, just these two.
I am not a lubricant engineer!!! just looking at the numbers to see if there are any consistent differences between the two approved Porsche fluids and all the others.
If you take a look below you will see that the approved fluids (Mobilube PTX and Spirax S5 ATE) both have almost identical numbers BUT the other 3 as well as just about all the other 75/90's out there have HIGHER Kinematic Viscosity (cSt) numbers AND LOWER Viscosity Index numbers. Could these differences be why some folks running the non-approved gear oils have to be a little more careful when cold? Good question!!!
The only gear oil I found specs on that seems to have really close properties to the Approved Mobilube & Shell Spirax is the Liqui-Moly 2048...
Mobil MOBILUBE PTX 75W-90 (Porsche approved)
Viscosity
cSt @ 40º C 77.6
cSt @ 100ºC 14.5
Viscosity Index 195
Flash Point, ºC 226
Pour Point, ºC -60
Density kg/m3 849
Shell Spirax S5 ATE 75W-90 (Porsche approved)
SAE J 306 75W-90 SAE Viscosity Grade
cSt @40 81
cSt @100 14.9
Viscosity Index 194
ISO 9262 35000 Dynamic Viscosity mPa s
0 3 ISO 12185 879 Density @15 C kg/m
0 ISO 2592 205 Flash Point (COC) C
Mobil Delvac 1 Gear Oil 75W-90
SAE Grade 75W-90
Viscosity, ASTM D 445
cSt @ 40ºC 120
cSt @ 100ºC 15.9
Viscosity Index 140
Pour Point, ºC, ASTM D 97 -48
Flash Point, ºC, ASTM D 92 205
Density @ 15ºC kg/l, ASTM D 4052 0.86
Redline 75W90 NS GL-5 Gear Oil
Vis @ 40°C, cSt 94.5
Vis @ 100°C, cSt 15.6
Viscosity Index 176
Pour Point, °C -45
Pour Point, °F -49
Brookfield Viscosity @ -40°C, Poise 400 @-40°C
**Liqui Moly 2048 ** (Very similar numbers to Porsche Approved)
Vis @ 40°C, cSt 80.9
Vis @ 100°C, cSt 14.3
Viscosity Index 184
Flash Point, °C 190
Pour Point, °C -60
Density kg/m3 855
05-01-2017, 10:51 PM
#37
Nordschleife Master
This is one of those examples of what I call internet telephone. Someone read something somewhere and only half understood it and reposted it incomplete. I will try to clear this up for all readers.
1. We do NOT call a gear driven differential a limited slip differential. Why? Because at the limit, like when you lift a wheel or put one in the dirt and have near zero traction, they go open. There is no limit to their slip control. We call them a torque biasing differential (TBD). Quaife calls theirs a Torsen because they bought the rights to the name. Torsen is a brand, like Quiafe is a brand. There are a bunch of different ways to design and set up a TBD. The Torsen way is one of many. Wavetrac makes TBDs too, though theirs has a gimmick, which they claim offers lock up under braking.
It's all mechanical across the gears. No clutches. Zero need for friction modifiers. Run whatever GL5 oil you want in a TBD, regardless of brand.
2. LSD. In Porsche world an LSD is almost always a Salisbury plate design. Let's ignore Detroit Lockers. They don't matter to us. The orginal OEM was ZF and people often call all Porsche LSDs ZFs, even though since 1996 GKN has been their OEM. Most LSDs you find on the market today chatter. This is doubly true with OEM LSDs because they are made out of hard grippy materials, the clutches that is. Friction modifiers in a gear oil make those clutches slide more smoothly against each other and run more quietly.
The problem with a Porsche is that it is a transaxle. What this means is the rear end (differential) and gear stack share the same oil bath. This poses some problems because the transmission gears have synchros and synchros do actually require a certain amount of friction to function. Too slippery and the synchros don't grab right on the shift. This is part of why I am not a big fan of LSD modifiers in the oil.
The other piece is proprietary. Our LSD clutches are not like what you find in most anything else. It is a proprietary ferrous alloy that is plasma sprayed onto the clutches. These are motorsports parts. While they are quite durable, what they were designed around was performance. When you introduce a friction modifier to one of our LSDs you are reducing the effective lock up. Ironically, because you are making them slip and slide more and bite less, in our experience they wear more quickly. There is no evidence that I know of to cross over our company position regarding additives to any competing brand on the market. Try running a Gikken LSD without additives. You'll hate the damn thing. Some LSDs do require additives to function well.
Our own product is the root of my beef not just with LSD additives, but with Redline NS. You hear people rave about the cold shift performance of Redline. It's because it is one of the most slippery oils out there. Take it on the track for an hour at 90 degrees ambient. The shift quality goes off the cliff when it gets hot. Our LSDs show terrible wear qualities with their oils, like half of normal. Do not ever use Redline with a Guard LSD in your car, please.
If you don't track your car, The hot shifing thing I talk about, it's a non-issue. This is a track specific beef and to be perfectly honest I have Redline NS in my street Subaru right now. So for most of you, even my personal bias against Redline wouldn't apply. I heard rumour that they were working on a new Porsche specific formulation when they were racing the Caymans with Bimmerworld/Next Level in IMSA. I would be interested to check out that oil if it ever comes to market.
Beyond that, use what shifts well for you. Change your oil every 10-15k. The factory service interval is insanely long. I don't let any of my cars ever go over 3 years on the same oil. It's oil. It's cheap compared to a $5-6k rebuild. Swepco is good. Delvac and PTX are good. Motul is good. Shell Spirax is good. Redline is good too, my bias not withstanding. Like John said, don't over think it or reinvent the wheel. Good oil is good oil these days.
1. We do NOT call a gear driven differential a limited slip differential. Why? Because at the limit, like when you lift a wheel or put one in the dirt and have near zero traction, they go open. There is no limit to their slip control. We call them a torque biasing differential (TBD). Quaife calls theirs a Torsen because they bought the rights to the name. Torsen is a brand, like Quiafe is a brand. There are a bunch of different ways to design and set up a TBD. The Torsen way is one of many. Wavetrac makes TBDs too, though theirs has a gimmick, which they claim offers lock up under braking.
It's all mechanical across the gears. No clutches. Zero need for friction modifiers. Run whatever GL5 oil you want in a TBD, regardless of brand.
2. LSD. In Porsche world an LSD is almost always a Salisbury plate design. Let's ignore Detroit Lockers. They don't matter to us. The orginal OEM was ZF and people often call all Porsche LSDs ZFs, even though since 1996 GKN has been their OEM. Most LSDs you find on the market today chatter. This is doubly true with OEM LSDs because they are made out of hard grippy materials, the clutches that is. Friction modifiers in a gear oil make those clutches slide more smoothly against each other and run more quietly.
The problem with a Porsche is that it is a transaxle. What this means is the rear end (differential) and gear stack share the same oil bath. This poses some problems because the transmission gears have synchros and synchros do actually require a certain amount of friction to function. Too slippery and the synchros don't grab right on the shift. This is part of why I am not a big fan of LSD modifiers in the oil.
The other piece is proprietary. Our LSD clutches are not like what you find in most anything else. It is a proprietary ferrous alloy that is plasma sprayed onto the clutches. These are motorsports parts. While they are quite durable, what they were designed around was performance. When you introduce a friction modifier to one of our LSDs you are reducing the effective lock up. Ironically, because you are making them slip and slide more and bite less, in our experience they wear more quickly. There is no evidence that I know of to cross over our company position regarding additives to any competing brand on the market. Try running a Gikken LSD without additives. You'll hate the damn thing. Some LSDs do require additives to function well.
Our own product is the root of my beef not just with LSD additives, but with Redline NS. You hear people rave about the cold shift performance of Redline. It's because it is one of the most slippery oils out there. Take it on the track for an hour at 90 degrees ambient. The shift quality goes off the cliff when it gets hot. Our LSDs show terrible wear qualities with their oils, like half of normal. Do not ever use Redline with a Guard LSD in your car, please.
If you don't track your car, The hot shifing thing I talk about, it's a non-issue. This is a track specific beef and to be perfectly honest I have Redline NS in my street Subaru right now. So for most of you, even my personal bias against Redline wouldn't apply. I heard rumour that they were working on a new Porsche specific formulation when they were racing the Caymans with Bimmerworld/Next Level in IMSA. I would be interested to check out that oil if it ever comes to market.
Beyond that, use what shifts well for you. Change your oil every 10-15k. The factory service interval is insanely long. I don't let any of my cars ever go over 3 years on the same oil. It's oil. It's cheap compared to a $5-6k rebuild. Swepco is good. Delvac and PTX are good. Motul is good. Shell Spirax is good. Redline is good too, my bias not withstanding. Like John said, don't over think it or reinvent the wheel. Good oil is good oil these days.
The following users liked this post:
996TS (10-14-2022)
05-01-2017, 11:12 PM
#38
Excellent post Matt ^^. Btw, neither your GT3 club LSD or the GT2 PRO I have in the car now have ever chattered. 100% seamless operation. I have always used Delvac and change it every 6-8 track days. Thanks for making an amazing product and the continued customer support.
Last edited by powdrhound; 05-02-2017 at 10:35 AM.
05-01-2017, 11:18 PM
#39
Rennlist Member
This is one of those examples of what I call internet telephone. Someone read something somewhere and only half understood it and reposted it incomplete. I will try to clear this up for all readers.
1. We do NOT call a gear driven differential a limited slip differential. Why? Because at the limit, like when you lift a wheel or put one in the dirt and have near zero traction, they go open. There is no limit to their slip control. We call them a torque biasing differential (TBD). Quaife calls theirs a Torsen because they bought the rights to the name. Torsen is a brand, like Quiafe is a brand. There are a bunch of different ways to design and set up a TBD. The Torsen way is one of many. Wavetrac makes TBDs too, though theirs has a gimmick, which they claim offers lock up under braking.
It's all mechanical across the gears. No clutches. Zero need for friction modifiers. Run whatever GL5 oil you want in a TBD, regardless of brand.
2. LSD. In Porsche world an LSD is almost always a Salisbury plate design. Let's ignore Detroit Lockers. They don't matter to us. The orginal OEM was ZF and people often call all Porsche LSDs ZFs, even though since 1996 GKN has been their OEM. Most LSDs you find on the market today chatter. This is doubly true with OEM LSDs because they are made out of hard grippy materials, the clutches that is. Friction modifiers in a gear oil make those clutches slide more smoothly against each other and run more quietly.
The problem with a Porsche is that it is a transaxle. What this means is the rear end (differential) and gear stack share the same oil bath. This poses some problems because the transmission gears have synchros and synchros do actually require a certain amount of friction to function. Too slippery and the synchros don't grab right on the shift. This is part of why I am not a big fan of LSD modifiers in the oil.
The other piece is proprietary. Our LSD clutches are not like what you find in most anything else. It is a proprietary ferrous alloy that is plasma sprayed onto the clutches. These are motorsports parts. While they are quite durable, what they were designed around was performance. When you introduce a friction modifier to one of our LSDs you are reducing the effective lock up. Ironically, because you are making them slip and slide more and bite less, in our experience they wear more quickly. There is no evidence that I know of to cross over our company position regarding additives to any competing brand on the market. Try running a Gikken LSD without additives. You'll hate the damn thing. Some LSDs do require additives to function well.
Our own product is the root of my beef not just with LSD additives, but with Redline NS. You hear people rave about the cold shift performance of Redline. It's because it is one of the most slippery oils out there. Take it on the track for an hour at 90 degrees ambient. The shift quality goes off the cliff when it gets hot. Our LSDs show terrible wear qualities with their oils, like half of normal. Do not ever use Redline with a Guard LSD in your car, please.
If you don't track your car, The hot shifing thing I talk about, it's a non-issue. This is a track specific beef and to be perfectly honest I have Redline NS in my street Subaru right now. So for most of you, even my personal bias against Redline wouldn't apply. I heard rumour that they were working on a new Porsche specific formulation when they were racing the Caymans with Bimmerworld/Next Level in IMSA. I would be interested to check out that oil if it ever comes to market.
Beyond that, use what shifts well for you. Change your oil every 10-15k. The factory service interval is insanely long. I don't let any of my cars ever go over 3 years on the same oil. It's oil. It's cheap compared to a $5-6k rebuild. Swepco is good. Delvac and PTX are good. Motul is good. Shell Spirax is good. Redline is good too, my bias not withstanding. Like John said, don't over think it or reinvent the wheel. Good oil is good oil these days.
1. We do NOT call a gear driven differential a limited slip differential. Why? Because at the limit, like when you lift a wheel or put one in the dirt and have near zero traction, they go open. There is no limit to their slip control. We call them a torque biasing differential (TBD). Quaife calls theirs a Torsen because they bought the rights to the name. Torsen is a brand, like Quiafe is a brand. There are a bunch of different ways to design and set up a TBD. The Torsen way is one of many. Wavetrac makes TBDs too, though theirs has a gimmick, which they claim offers lock up under braking.
It's all mechanical across the gears. No clutches. Zero need for friction modifiers. Run whatever GL5 oil you want in a TBD, regardless of brand.
2. LSD. In Porsche world an LSD is almost always a Salisbury plate design. Let's ignore Detroit Lockers. They don't matter to us. The orginal OEM was ZF and people often call all Porsche LSDs ZFs, even though since 1996 GKN has been their OEM. Most LSDs you find on the market today chatter. This is doubly true with OEM LSDs because they are made out of hard grippy materials, the clutches that is. Friction modifiers in a gear oil make those clutches slide more smoothly against each other and run more quietly.
The problem with a Porsche is that it is a transaxle. What this means is the rear end (differential) and gear stack share the same oil bath. This poses some problems because the transmission gears have synchros and synchros do actually require a certain amount of friction to function. Too slippery and the synchros don't grab right on the shift. This is part of why I am not a big fan of LSD modifiers in the oil.
The other piece is proprietary. Our LSD clutches are not like what you find in most anything else. It is a proprietary ferrous alloy that is plasma sprayed onto the clutches. These are motorsports parts. While they are quite durable, what they were designed around was performance. When you introduce a friction modifier to one of our LSDs you are reducing the effective lock up. Ironically, because you are making them slip and slide more and bite less, in our experience they wear more quickly. There is no evidence that I know of to cross over our company position regarding additives to any competing brand on the market. Try running a Gikken LSD without additives. You'll hate the damn thing. Some LSDs do require additives to function well.
Our own product is the root of my beef not just with LSD additives, but with Redline NS. You hear people rave about the cold shift performance of Redline. It's because it is one of the most slippery oils out there. Take it on the track for an hour at 90 degrees ambient. The shift quality goes off the cliff when it gets hot. Our LSDs show terrible wear qualities with their oils, like half of normal. Do not ever use Redline with a Guard LSD in your car, please.
If you don't track your car, The hot shifing thing I talk about, it's a non-issue. This is a track specific beef and to be perfectly honest I have Redline NS in my street Subaru right now. So for most of you, even my personal bias against Redline wouldn't apply. I heard rumour that they were working on a new Porsche specific formulation when they were racing the Caymans with Bimmerworld/Next Level in IMSA. I would be interested to check out that oil if it ever comes to market.
Beyond that, use what shifts well for you. Change your oil every 10-15k. The factory service interval is insanely long. I don't let any of my cars ever go over 3 years on the same oil. It's oil. It's cheap compared to a $5-6k rebuild. Swepco is good. Delvac and PTX are good. Motul is good. Shell Spirax is good. Redline is good too, my bias not withstanding. Like John said, don't over think it or reinvent the wheel. Good oil is good oil these days.
05-01-2017, 11:57 PM
#40
Nordschleife Master
Excellent post Matt ^^. Btw, neither the GT3 club LSD or the GT2 PRO I have in the car now have ever chattered. 100% seamless operation. I have always used Delvac and change it every 6-8 track days. Thanks for making an amazing product and the continued customer support.
05-05-2017, 12:48 PM
#41
Rennlist Member
Here are the data sheets for the 2 Mobil Gear oils and Shell's offering that meet Porsche's performance standard as well Mobil One's standard OTC GL-5 offering;
Mobilube PTX 75w90 - OE fill, works great with LSD, especially good in colder weather, smoothest shifts with OE synchronizers. $39USD/liter
Mobilube Delvac SHC 75w90 Porsche Motorsports factory fill -
owners with daily driver Porsches tend to try once and then go back to something else. Plus absolutely horrible in cold weather. $42USD/gal
Shell Spirax S5 ATE 75w90 - Also OE fill
Mobilube LS 75w90 - OTC at most retailers, cheapest, designed for LSD, shifting is not as smooth as PTX/SHC. $13USD/qt
Mobilube PTX 75w90 - OE fill, works great with LSD, especially good in colder weather, smoothest shifts with OE synchronizers. $39USD/liter
Mobilube Delvac SHC 75w90 Porsche Motorsports factory fill -
owners with daily driver Porsches tend to try once and then go back to something else. Plus absolutely horrible in cold weather. $42USD/gal
Shell Spirax S5 ATE 75w90 - Also OE fill
Mobilube LS 75w90 - OTC at most retailers, cheapest, designed for LSD, shifting is not as smooth as PTX/SHC. $13USD/qt
Delvac is per gallon
Big difference.
05-05-2017, 08:54 PM
#42
Technical Guru
Rennlist Member
Rennlist Member
04-30-2021, 10:35 PM
#44
This is one of those examples of what I call internet telephone. Someone read something somewhere and only half understood it and reposted it incomplete. I will try to clear this up for all readers.
1. We do NOT call a gear driven differential a limited slip differential. Why? Because at the limit, like when you lift a wheel or put one in the dirt and have near zero traction, they go open. There is no limit to their slip control. We call them a torque biasing differential (TBD). Quaife calls theirs a Torsen because they bought the rights to the name. Torsen is a brand, like Quiafe is a brand. There are a bunch of different ways to design and set up a TBD. The Torsen way is one of many. Wavetrac makes TBDs too, though theirs has a gimmick, which they claim offers lock up under braking.
It's all mechanical across the gears. No clutches. Zero need for friction modifiers. Run whatever GL5 oil you want in a TBD, regardless of brand.
2. LSD. In Porsche world an LSD is almost always a Salisbury plate design. Let's ignore Detroit Lockers. They don't matter to us. The orginal OEM was ZF and people often call all Porsche LSDs ZFs, even though since 1996 GKN has been their OEM. Most LSDs you find on the market today chatter. This is doubly true with OEM LSDs because they are made out of hard grippy materials, the clutches that is. Friction modifiers in a gear oil make those clutches slide more smoothly against each other and run more quietly.
The problem with a Porsche is that it is a transaxle. What this means is the rear end (differential) and gear stack share the same oil bath. This poses some problems because the transmission gears have synchros and synchros do actually require a certain amount of friction to function. Too slippery and the synchros don't grab right on the shift. This is part of why I am not a big fan of LSD modifiers in the oil.
The other piece is proprietary. Our LSD clutches are not like what you find in most anything else. It is a proprietary ferrous alloy that is plasma sprayed onto the clutches. These are motorsports parts. While they are quite durable, what they were designed around was performance. When you introduce a friction modifier to one of our LSDs you are reducing the effective lock up. Ironically, because you are making them slip and slide more and bite less, in our experience they wear more quickly. There is no evidence that I know of to cross over our company position regarding additives to any competing brand on the market. Try running a Gikken LSD without additives. You'll hate the damn thing. Some LSDs do require additives to function well.
Our own product is the root of my beef not just with LSD additives, but with Redline NS. You hear people rave about the cold shift performance of Redline. It's because it is one of the most slippery oils out there. Take it on the track for an hour at 90 degrees ambient. The shift quality goes off the cliff when it gets hot. Our LSDs show terrible wear qualities with their oils, like half of normal. Do not ever use Redline with a Guard LSD in your car, please.
If you don't track your car, The hot shifing thing I talk about, it's a non-issue. This is a track specific beef and to be perfectly honest I have Redline NS in my street Subaru right now. So for most of you, even my personal bias against Redline wouldn't apply. I heard rumour that they were working on a new Porsche specific formulation when they were racing the Caymans with Bimmerworld/Next Level in IMSA. I would be interested to check out that oil if it ever comes to market.
Beyond that, use what shifts well for you. Change your oil every 10-15k. The factory service interval is insanely long. I don't let any of my cars ever go over 3 years on the same oil. It's oil. It's cheap compared to a $5-6k rebuild. Swepco is good. Delvac and PTX are good. Motul is good. Shell Spirax is good. Redline is good too, my bias not withstanding. Like John said, don't over think it or reinvent the wheel. Good oil is good oil these days.
1. We do NOT call a gear driven differential a limited slip differential. Why? Because at the limit, like when you lift a wheel or put one in the dirt and have near zero traction, they go open. There is no limit to their slip control. We call them a torque biasing differential (TBD). Quaife calls theirs a Torsen because they bought the rights to the name. Torsen is a brand, like Quiafe is a brand. There are a bunch of different ways to design and set up a TBD. The Torsen way is one of many. Wavetrac makes TBDs too, though theirs has a gimmick, which they claim offers lock up under braking.
It's all mechanical across the gears. No clutches. Zero need for friction modifiers. Run whatever GL5 oil you want in a TBD, regardless of brand.
2. LSD. In Porsche world an LSD is almost always a Salisbury plate design. Let's ignore Detroit Lockers. They don't matter to us. The orginal OEM was ZF and people often call all Porsche LSDs ZFs, even though since 1996 GKN has been their OEM. Most LSDs you find on the market today chatter. This is doubly true with OEM LSDs because they are made out of hard grippy materials, the clutches that is. Friction modifiers in a gear oil make those clutches slide more smoothly against each other and run more quietly.
The problem with a Porsche is that it is a transaxle. What this means is the rear end (differential) and gear stack share the same oil bath. This poses some problems because the transmission gears have synchros and synchros do actually require a certain amount of friction to function. Too slippery and the synchros don't grab right on the shift. This is part of why I am not a big fan of LSD modifiers in the oil.
The other piece is proprietary. Our LSD clutches are not like what you find in most anything else. It is a proprietary ferrous alloy that is plasma sprayed onto the clutches. These are motorsports parts. While they are quite durable, what they were designed around was performance. When you introduce a friction modifier to one of our LSDs you are reducing the effective lock up. Ironically, because you are making them slip and slide more and bite less, in our experience they wear more quickly. There is no evidence that I know of to cross over our company position regarding additives to any competing brand on the market. Try running a Gikken LSD without additives. You'll hate the damn thing. Some LSDs do require additives to function well.
Our own product is the root of my beef not just with LSD additives, but with Redline NS. You hear people rave about the cold shift performance of Redline. It's because it is one of the most slippery oils out there. Take it on the track for an hour at 90 degrees ambient. The shift quality goes off the cliff when it gets hot. Our LSDs show terrible wear qualities with their oils, like half of normal. Do not ever use Redline with a Guard LSD in your car, please.
If you don't track your car, The hot shifing thing I talk about, it's a non-issue. This is a track specific beef and to be perfectly honest I have Redline NS in my street Subaru right now. So for most of you, even my personal bias against Redline wouldn't apply. I heard rumour that they were working on a new Porsche specific formulation when they were racing the Caymans with Bimmerworld/Next Level in IMSA. I would be interested to check out that oil if it ever comes to market.
Beyond that, use what shifts well for you. Change your oil every 10-15k. The factory service interval is insanely long. I don't let any of my cars ever go over 3 years on the same oil. It's oil. It's cheap compared to a $5-6k rebuild. Swepco is good. Delvac and PTX are good. Motul is good. Shell Spirax is good. Redline is good too, my bias not withstanding. Like John said, don't over think it or reinvent the wheel. Good oil is good oil these days.
Hi Matt,
I purchased a 996.2 c2 manual car in Jan this year with your LSD in it, recently my gear box crunched at high speeds going from 3rd into 4th gear at the race track
The next day my indy shop changed out the oil to the Liqui Moly and then I saw this post, is this oil ok with your LSD?
There was quite a bit of silvery coloured oil that came out.
I probably track once a year with very frequent hard driving through the the mountains.
Cheers from downunder.
Jim