Transmission fluid for LSD
Race Director
Joined: Sep 2006
Posts: 19,035
Likes: 269
From: Bentonville, AR
$23/quart is not bad. Just takes a couple of quarts IIRC. Sometimes my service manager even gives me a break on the fluid price. Last time for my Boxster he charged me $5/quart as the shop has some left over from some warranty work. Labor is 0.3 hour. One of the cheapest services available and that's good because I hate to change my car's transmission fluid. (The Turbo takes a bit more fluid and requires a bit more labor, but still not much.)
The factory transmission fluid is pretty good. I point out my 02 Boxster has had that almost exclusively -- once I think a dealer or an indy shop put in something else as cold shifting improved at the expense of hot shifting -- and the transmission has almost 276K miles on it. Still shifts just fine. Quiet too.
The factory transmission fluid is pretty good. I point out my 02 Boxster has had that almost exclusively -- once I think a dealer or an indy shop put in something else as cold shifting improved at the expense of hot shifting -- and the transmission has almost 276K miles on it. Still shifts just fine. Quiet too.
Racer
Joined: Nov 2012
Posts: 284
Likes: 1
From: Alberta, Canada
Motul makes two gear oils in the 75/90 grade, one for regular, and one for LS differentials. On the links below you can see where they differ in their specs.
LSD http://motul.speclube.com/products/a...0-ls-75w90-1l/
non LSD http://motul.speclube.com/products/a...-300-75w90-1l/
LSD http://motul.speclube.com/products/a...0-ls-75w90-1l/
non LSD http://motul.speclube.com/products/a...-300-75w90-1l/
Thread Starter
Rennlist Member
Joined: Dec 2011
Posts: 4,442
Likes: 1,820
From: Gig Harbor, WA
Alright, one more question on changing the transmission fluid:
Is refilling this like on a diff or a lot of other transmissions where you fill it until the fluid starts to drip from the fill hole, or do I need to actually measure out 2.85 quarts and fill it with that much?
Is refilling this like on a diff or a lot of other transmissions where you fill it until the fluid starts to drip from the fill hole, or do I need to actually measure out 2.85 quarts and fill it with that much?
Nordschleife Master
Joined: May 2005
Posts: 7,326
Likes: 77
Alright, one more question on changing the transmission fluid:
Is refilling this like on a diff or a lot of other transmissions where you fill it until the fluid starts to drip from the fill hole, or do I need to actually measure out 2.85 quarts and fill it with that much?
Is refilling this like on a diff or a lot of other transmissions where you fill it until the fluid starts to drip from the fill hole, or do I need to actually measure out 2.85 quarts and fill it with that much?
Rennlist Member
Joined: Jan 2014
Posts: 60
Likes: 0
Motul makes two gear oils in the 75/90 grade, one for regular, and one for LS differentials. On the links below you can see where they differ in their specs.
LSD http://motul.speclube.com/products/a...0-ls-75w90-1l/
non LSD http://motul.speclube.com/products/a...-300-75w90-1l/
LSD http://motul.speclube.com/products/a...0-ls-75w90-1l/
non LSD http://motul.speclube.com/products/a...-300-75w90-1l/
There is periodically a discussion of this issue on ferrarichat. Ferraris, Panteras, Porsches, even rear-engine Fiats use transaxles, where the transmission and rear axle are combined into one housing.
If you use an oil designed for an LSD axle it is too slippery for proper synchromesh engagement and you will wear them out prematurely. The answer is Red Line 75W-90NS, which does NOT have the friction modifiers. If you feel the LSD clutches binding when making a sharp turn you can add a tiny bit of the modifier until that stops, but most people do not find that necessary.
The advantage of synthetic oils like the Red Line is that it is less viscous at low temps-- hence easier shifting until it warms up. I would not recommend using non-synthetic oil-- the Red Line is not THAT expensive. I get it on Amazon with free shipping.
Rennlist Member
Joined: Aug 2006
Posts: 9,213
Likes: 1,908
From: Chicago, IL
I don’t know how long it’s been since the trans/diff oil has been changed in my 99 c2 with factory LSD.
Its not exactly cheap fluid to replace either, but I will probably stick with the Porsche brand, as I’ve done that in the past and never had any issues with my transmissions.
The shifting on my car is quite difficult when it comes to putting it in first gear unless I’m stopped. And when the trans is cold, all the gears are difficult to grab.
I just wish there There was a way for me to know when the oil was last replaced, since I’m not sure if replacing it will result in easier shifting. Like I said, not exactly cheap oil.
Its not exactly cheap fluid to replace either, but I will probably stick with the Porsche brand, as I’ve done that in the past and never had any issues with my transmissions.
The shifting on my car is quite difficult when it comes to putting it in first gear unless I’m stopped. And when the trans is cold, all the gears are difficult to grab.
I just wish there There was a way for me to know when the oil was last replaced, since I’m not sure if replacing it will result in easier shifting. Like I said, not exactly cheap oil.
Rennlist Member
Joined: Feb 2015
Posts: 707
Likes: 20
I used the Fuchs stuff . I'm running a factory lsd that's had the full guard upgrade , clutches , plates , 40/60 ramps etc.
https://www.pelicanparts.com/catalog..._pg1.htm#item0
https://www.pelicanparts.com/catalog..._pg1.htm#item0
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Michael S. Palmer
Rennlist Member
Joined: Dec 2013
Posts: 4,777
Likes: 284
From: Edmond, OK
I use Motul and have been pretty happy with it.
Sounds like your synchronizers could use a refresh. Also, the chances are that your LSD is completely worn out. A good was to test is to jack up one rear tire. Release the emergency brake but put it into first gear. Make sure you are on a flat surface obviously. Now take your torque wrench, set it to 10 or 20, put it on a lug, and see if you can spin the wheel with it. If you can, your LSD is shot. If it requires 50 or higher, it still probably has some life in it. Over 80 and it’s probably had a rebuild recently.
Sounds like your synchronizers could use a refresh. Also, the chances are that your LSD is completely worn out. A good was to test is to jack up one rear tire. Release the emergency brake but put it into first gear. Make sure you are on a flat surface obviously. Now take your torque wrench, set it to 10 or 20, put it on a lug, and see if you can spin the wheel with it. If you can, your LSD is shot. If it requires 50 or higher, it still probably has some life in it. Over 80 and it’s probably had a rebuild recently.
Rennlist Member
Joined: Aug 2006
Posts: 9,213
Likes: 1,908
From: Chicago, IL
I use Motul and have been pretty happy with it.
Sounds like your synchronizers could use a refresh. Also, the chances are that your LSD is completely worn out. A good was to test is to jack up one rear tire. Release the emergency brake but put it into first gear. Make sure you are on a flat surface obviously. Now take your torque wrench, set it to 10 or 20, put it on a lug, and see if you can spin the wheel with it. If you can, your LSD is shot. If it requires 50 or higher, it still probably has some life in it. Over 80 and it’s probably had a rebuild recently.
Sounds like your synchronizers could use a refresh. Also, the chances are that your LSD is completely worn out. A good was to test is to jack up one rear tire. Release the emergency brake but put it into first gear. Make sure you are on a flat surface obviously. Now take your torque wrench, set it to 10 or 20, put it on a lug, and see if you can spin the wheel with it. If you can, your LSD is shot. If it requires 50 or higher, it still probably has some life in it. Over 80 and it’s probably had a rebuild recently.
Rennlist Member
Joined: May 2016
Posts: 1,163
Likes: 277
From: Michigan
I'm hoping I won't get flamed for bringing in info from non-Porsches. :-)
There is periodically a discussion of this issue on ferrarichat. Ferraris, Panteras, Porsches, even rear-engine Fiats use transaxles, where the transmission and rear axle are combined into one housing.
If you use an oil designed for an LSD axle it is too slippery for proper synchromesh engagement and you will wear them out prematurely. The answer is Red Line 75W-90NS, which does NOT have the friction modifiers. If you feel the LSD clutches binding when making a sharp turn you can add a tiny bit of the modifier until that stops, but most people do not find that necessary.
The advantage of synthetic oils like the Red Line is that it is less viscous at low temps-- hence easier shifting until it warms up. I would not recommend using non-synthetic oil-- the Red Line is not THAT expensive. I get it on Amazon with free shipping.
There is periodically a discussion of this issue on ferrarichat. Ferraris, Panteras, Porsches, even rear-engine Fiats use transaxles, where the transmission and rear axle are combined into one housing.
If you use an oil designed for an LSD axle it is too slippery for proper synchromesh engagement and you will wear them out prematurely. The answer is Red Line 75W-90NS, which does NOT have the friction modifiers. If you feel the LSD clutches binding when making a sharp turn you can add a tiny bit of the modifier until that stops, but most people do not find that necessary.
The advantage of synthetic oils like the Red Line is that it is less viscous at low temps-- hence easier shifting until it warms up. I would not recommend using non-synthetic oil-- the Red Line is not THAT expensive. I get it on Amazon with free shipping.
I just picked up my 99C2 MT with LSD, and had asked the local indy shop to change the transaxle fluid. I hadn't done any research, but they used the redline 75W 90NS as mentioned above. I need to ask them more about the background.
Rennlist Member
Joined: Aug 2006
Posts: 9,213
Likes: 1,908
From: Chicago, IL
I use Motul and have been pretty happy with it.
Sounds like your synchronizers could use a refresh. Also, the chances are that your LSD is completely worn out. A good was to test is to jack up one rear tire. Release the emergency brake but put it into first gear. Make sure you are on a flat surface obviously. Now take your torque wrench, set it to 10 or 20, put it on a lug, and see if you can spin the wheel with it. If you can, your LSD is shot. If it requires 50 or higher, it still probably has some life in it. Over 80 and it’s probably had a rebuild recently.
Sounds like your synchronizers could use a refresh. Also, the chances are that your LSD is completely worn out. A good was to test is to jack up one rear tire. Release the emergency brake but put it into first gear. Make sure you are on a flat surface obviously. Now take your torque wrench, set it to 10 or 20, put it on a lug, and see if you can spin the wheel with it. If you can, your LSD is shot. If it requires 50 or higher, it still probably has some life in it. Over 80 and it’s probably had a rebuild recently.
Rennlist Member
Joined: Aug 2006
Posts: 9,213
Likes: 1,908
From: Chicago, IL
I’ve read up on folks using different branded oils in leu of the Porsche factory fill, and I don’t think the factory fill is the only fluid that will work as intended. I’m guessing not all of these oils have the exact same viscosity as each other, so some oils might result in easier shifting than others at different temperatures with different tradeoffs. I tend to be gentle when shifting, so I could probably get by with an oil that’s more forgiving and easier to shift, whereas other folks that track their car’s light choose an oil that’s offers slightly better protection when hot.
Rennlist Member
Joined: May 2016
Posts: 1,163
Likes: 277
From: Michigan
And how does it shift?
I’ve read up on folks using different branded oils in leu of the Porsche factory fill, and I don’t think the factory fill is the only fluid that will work as intended. I’m guessing not all of these oils have the exact same viscosity as each other, so some oils might result in easier shifting than others at different temperatures with different tradeoffs. I tend to be gentle when shifting, so I could probably get by with an oil that’s more forgiving and easier to shift, whereas other folks that track their car’s light choose an oil that’s offers slightly better protection when hot.