Question: C5 Maintenance

[Sbruce]

I've found answers to most of my questions about lubricants for the engine and rear end, but there seems to be a lot of conjecture on six-speed transmission lube. Does anyone have any factual information on what to use, how much to use and how to drain and fill the transmission? I have a 2001 coupe with the manual six-speed.

Thanks in advance
Bruce

 

[Toms007]

First, I want to welcome you to CAC. We have some of the best experts here and one of them should be by soon to answer your question.

 

[kpic]

Welcome to CAC.

Do a search on YouTube for "changing c5 manual transmission fluid" Froggy has quite a few videos for maintenance.

 

[LLC5]

I've found answers to most of my questions about lubricants for the engine and rear end, but there seems to be a lot of conjecture on six-speed transmission lube. Does anyone have any factual information on what to use, how much to use and how to drain and fill the transmission? I have a 2001 coupe with the manual six-speed.

Thanks in advance
Bruce

The only factual information that I have for the C5 6 spd manual transmission is what I have tried. GM's latest transmission fluid worked ok, Dexron 3 and 6 worked ok, Amsoil worked ok, but the best shifting improvement came when I started using Redline D4 ATF fluid and it made a noticeable difference is shifting quality. Drain the fluid while it is hot, and jacking the front of the vehicle up a little from level will drain about another 1/4 qt. Total refill will take between 3.0-3.5 qts. depending on how much is drained out. Make sure that the "shifter adjustment" is performed correctly as it is crucial to shifting performance. Good luck with it.

 

[Hib Halverson]

Building on what "LLC5" says above, there are a number of options for lubricant in the Tremec six-speed manual. What you use depends on your budget and to what duty cycle the car is subjected.

If cost is a concern and the duty cycle is normal driving, the factory specified manual transmission lubricant is ok.

If cost is a lesser concern and normal driving is the cycle, Red Line D4 is an excellent choice.

If cost is lesser concern and the duty cycle is aggressive driving in warm/hot weather, either Red Line MTL or Gibbs Driven STF are both good choices. Each is formulated for high-performance street use and occasional racing.

Is cost is not a concern and the duty cycle is racing, Red Line Superlight Shockproof Gear Lubricant is an excellent choice. It's probably about the highest-performance low-viscosity gear lube you can get. I use it in both my C5 and my C6. There is one slight negative of Red Line SLSP and that's cold shift quality is not so good, but as soon as the lubricant warms just a bit, that issue goes away. It doesn't even need to get to operating temperature. It just needs to get from cold to lukewarm and the shift quality improves greatly. Once the trans is at operating temperature shift feel is better than what you get with D4.

Lastly, let me say that all the high-dollor lubricants on earth will not improve shift feel if either the clutch needs to be bled or the shift linkage is out of adjustment. On a 13 year old car, you may want to check those two items.

 

[Sbruce]

More on lubes...

I appreciate all the responses, I am going with the Redline MTL for the transmission. I am going to change the rear end fluid and use Mobil-1 75w90. Should I use a friction modifier with that, or just go with the straight syn 75w90 lube?

Thanks again for the help.

Oh, how does one get a picture in their member info n the left column. I have managed to get one in an album but not in my profile.

 

[dadaroo]

Here is what the 2001 Owners Manual says





SAE 75W-90 Synthetic Axle
Lubricant (GM Part No. 12378261
or equivalent) meeting GM
Specification 9986115. With a
complete drain and refill add
4 ounces (118 ml) of Limited-Slip
Axle Lubricant Additive (GM Part
No. 1052358 or equivalent) where
required. See “Rear Axle” in
the Index.



With that said the Mobil 1 gear lube is used by a lot of C5 owners with and without the additive. Mobil 1 says for the C6 you need to add some additional additive. Not sure what is difference is between the two diffs. or they just were never asked about the C5. The C6 info is on their website.

If I used Mobil 1 I would add half of the GM recommended amount of any additive.

There are many other options like Redline and this one:

Mark's 2004 Corvette Z06