Gear oil question
12-27-2005, 12:22 PM
#1
Rennlist
Lifetime Member
Lifetime Member
Thread Starter
Gear oil question
Hi guys,
Sorry to bring a 996 subject on the 993 board, as I posted these questions on the 996 board and didn't receive a single response.... I wonder about this........Maybe a interior color question would draw more attention.....
Bought an used 99 C4 couple month ago been enjoy driving it so far (Still have my 993), much effortless to drive compare to the 993 and A/C works great. (Yes, still using A/C in California).
So far knock on wood everything seems to be in working order except some minor crappy loose interior trim noise, minor exhaust rattling sound and the way the transmission shifts, especially when it is cold. It is almost impossible to shift to first gear unless the car is stopped completely for few seconds when cold, and very notchy going to 2nd. Once the car is fully warmed up it is buttery smooth. So I want to change the transmission gear oil to see if it would make any difference, along with the motor oil. (Previous owner have been using 15w50, I want to change to 0w40 as it is what the factory fill is now for the 996)
I have been checking the archives and also browsed the Renntech board, and this is what I have gathered so far, just need some confirmation from some of you that have some experiences with this.
This is what I know so far:
(1). I need to use oil that will protect both the differential and provide enough friction for the synchros to work since the transmission/differential unit in the 911 is a combined unit in design (Thus share the same fluid)
(2). Mobilube PTX (synthetic) 75W-90 GL-4, GL-5 is what the factory recommends. The GL-4 rating supposely provides enough friction needed for the synchros to work properly, and the GL-5 provides protection for the differential under high pressure environment. So the gear oil needs both the GL-4 and GL5 rating and mix.
(3). Can't get Mobil PTX here unless you want to pay outrageous price from the dealer.
(4). Don't remember the 993 requiring GL4 rating gear oil. And interesting enough when I changed my 993's gear oil using Mobil 1 75w90 GL5 I did have some issues with the synchros when cold. (Changed to Swepco sovled that issue) I know that the 993 comes from the factory with a different fill which is not avaliable in the US. So could the owner's manual have provided insufficient information as to the correct gear oil to use in a 993?
(5). I was told that the Front tranaxle uses the same oil as the transmission GL4/5. (On a C4) Just curious of the construction component of the front transaxle if using GL4/5 would be suited. As the factory shop manual states using ATF fluid, which was later found to be a typo.
(6). Someone recommended using Silkolene Silktran SYN 5 API GL4/5 75W/90 as a substitute, which is available in the US for $15 / liter. Have anyone tried this?
(7). What oil recommendations do you guys have?
Just curious if I am on the right track?
The shop manual is also not too clear on this subject, so I want to ask the board to see if anyone can shine a light on this subject.
TIA
Sorry to bring a 996 subject on the 993 board, as I posted these questions on the 996 board and didn't receive a single response.... I wonder about this........Maybe a interior color question would draw more attention.....
Bought an used 99 C4 couple month ago been enjoy driving it so far (Still have my 993), much effortless to drive compare to the 993 and A/C works great. (Yes, still using A/C in California).
So far knock on wood everything seems to be in working order except some minor crappy loose interior trim noise, minor exhaust rattling sound and the way the transmission shifts, especially when it is cold. It is almost impossible to shift to first gear unless the car is stopped completely for few seconds when cold, and very notchy going to 2nd. Once the car is fully warmed up it is buttery smooth. So I want to change the transmission gear oil to see if it would make any difference, along with the motor oil. (Previous owner have been using 15w50, I want to change to 0w40 as it is what the factory fill is now for the 996)
I have been checking the archives and also browsed the Renntech board, and this is what I have gathered so far, just need some confirmation from some of you that have some experiences with this.
This is what I know so far:
(1). I need to use oil that will protect both the differential and provide enough friction for the synchros to work since the transmission/differential unit in the 911 is a combined unit in design (Thus share the same fluid)
(2). Mobilube PTX (synthetic) 75W-90 GL-4, GL-5 is what the factory recommends. The GL-4 rating supposely provides enough friction needed for the synchros to work properly, and the GL-5 provides protection for the differential under high pressure environment. So the gear oil needs both the GL-4 and GL5 rating and mix.
(3). Can't get Mobil PTX here unless you want to pay outrageous price from the dealer.
(4). Don't remember the 993 requiring GL4 rating gear oil. And interesting enough when I changed my 993's gear oil using Mobil 1 75w90 GL5 I did have some issues with the synchros when cold. (Changed to Swepco sovled that issue) I know that the 993 comes from the factory with a different fill which is not avaliable in the US. So could the owner's manual have provided insufficient information as to the correct gear oil to use in a 993?
(5). I was told that the Front tranaxle uses the same oil as the transmission GL4/5. (On a C4) Just curious of the construction component of the front transaxle if using GL4/5 would be suited. As the factory shop manual states using ATF fluid, which was later found to be a typo.
(6). Someone recommended using Silkolene Silktran SYN 5 API GL4/5 75W/90 as a substitute, which is available in the US for $15 / liter. Have anyone tried this?
(7). What oil recommendations do you guys have?
Just curious if I am on the right track?
The shop manual is also not too clear on this subject, so I want to ask the board to see if anyone can shine a light on this subject.
TIA
12-27-2005, 12:45 PM
#2
King of Cool
Rennlist Member
Rennlist Member
Hello Robin,
Personally I'd use PTX since you don't need that much (3 liters) so price isn't that big of an issue (I assume it's not something lke $300 / liter).
For better info, check Renntech forum post about the 996 tranny oil
Personally I'd use PTX since you don't need that much (3 liters) so price isn't that big of an issue (I assume it's not something lke $300 / liter).
For better info, check Renntech forum post about the 996 tranny oil
12-27-2005, 01:47 PM
#3
Originally Posted by Robin 993DX
And interesting enough when I changed my 993's gear oil using Mobil 1 75w90 GL5 I did have some issues with the synchros when cold. (Changed to Swepco sovled that issue)
12-27-2005, 01:55 PM
#4
PS Armorer
Rennlist Member
Rennlist Member
My experience was identical to yours in (4) above regarding Mobil 1 75w90 and Swepco.
Others have had different experiences-some swear by Mobil 1.
I think the summary of all this is that you should consider identifying all the products that will provide adequate protection and then start trying them 1 by 1 until you find what works. Maybe not the most cost-efficient route, but at least you'll know what works for your situation and what doesn't. It seems there is too much variation in driving conditions, ambient and operating temperatures, gearbox condition, shifting "feel," etc... for there to be one right answer (at least on 993s).
Jason
Others have had different experiences-some swear by Mobil 1.
I think the summary of all this is that you should consider identifying all the products that will provide adequate protection and then start trying them 1 by 1 until you find what works. Maybe not the most cost-efficient route, but at least you'll know what works for your situation and what doesn't. It seems there is too much variation in driving conditions, ambient and operating temperatures, gearbox condition, shifting "feel," etc... for there to be one right answer (at least on 993s).
Jason
12-27-2005, 01:58 PM
#5
Rennlist
Lifetime Member
Lifetime Member
Thread Starter
Kolbjorn,
I did tried the Redline mix in my 993 for awhile, still same problem with cold shifting. The mixture ratio I used were 3 quart 75w90 and 1 quart 75w80 red line synthetic fluids, Dan from Redline also recommended adding a little friction modifier into the mix to help with the Synchros. I ended up with using Swepco 201 which resolved majority of my cold shifting issues.
I did tried the Redline mix in my 993 for awhile, still same problem with cold shifting. The mixture ratio I used were 3 quart 75w90 and 1 quart 75w80 red line synthetic fluids, Dan from Redline also recommended adding a little friction modifier into the mix to help with the Synchros. I ended up with using Swepco 201 which resolved majority of my cold shifting issues.
