Ok so what is the official on trans fluid? I have an '98 mn6. I know that the side says only use dextron III. I have also seen posts on the forum about synthetic fluids and paper blockers. So do all '98's have the paper? I would like to change my fluid as 1st and 2nd are becoming rather hard shifts.
I want to get the best fluid I can but don't want to make a bigger mess in the process.
Thanks!

 

 

Thanks! That really helped me out.

 

do a search for royal purple synchromax. there are guys on both sides of this issue, but i think that rp says their synthetic is ok for c5s

 

amsoil torque drive is also reputed to work well with out paper backed gears.

 

If you want to trust the folks that designed and built your vehicle you only have two choices. They are GM manual trans fluid part # 88861800 or Dexron VI. These are the only products certified for use. In order for a transmission fluid to carry a Dexron VI on their label the manufacture has to prove their product meets the requirements set by GM. If you plan to use anything other than the two suggested above, make sure you check that the company selling you their non-certified product, will cover for damages to your transmission if traced to their product. It is your vehicle, use what you feel would be best. In my personal vehicle I would use nothing but Dexron VI. Dexron VI is FULLY backward compatible with application that required Dexron III. One other word of caution, many companies will have on their label that their product is DexIII, Dex3, Dexron III or any like terms compatible. This means nothing!! Short and simple. Since 2006 anyone can use this term and NO ONE licenses the use of Dexron III. No testing no requirement to use this name. For more in-depth reading, check this link.

 

Eric - Thanks for the information!

 

I also am trying to convince myself this is the way to go, BUT it says on the bottle do not use in manual transmissions or power steering pumps. Has the GM information changed?

 

I have tried a few different fluids and the one that gave me the results I was looking for is Royal Purple Synchromax. I've been using it for a few years with only positive results.

 

 

Once again you've been a great help.

 

Even though Eric is a GM engineer, people still disregard his suggestions. So the guy posts a link to the GM Tech Link site, which tells you everything you need to know about Dexron 4........and yet it's still unclear?

If you truly feel uncomfortable with using Dexron 4, or question it's backward compatibility for use in a C5 manual transmission, then follow this direction(from the link Eric provided):

TIP: Any vehicle that previously used DEXRON-III for a manual transmission or transfer case should now use p/n 88861800 (88861801 in Canada) Manual Transmission and Transfer Case Fluid. And power steering systems should now use p/n 89020661 (89021183 in Canada) Power Steering Fluid.

 

That is a "good" reply, but how am I to know that Eric was or is a GM engineer. His post doesn't indicate whether he even has a manual transmission, it just says he would use it in his car.
Please check out the replies to this thread:

http://forums.corvetteforum.com/c6-z...8861800-a.html

This is the reason for my hesitance to install the DEXRON VI. What is this dexron 4 you wrote about anyway? The dexron vi bottle says do not use in manual transmissions so who's right the guy who designed the bottle or Eric. I guess I can't go wrong with the 88861800 as suggested by Eric and the manufacturer.

 

My mistake......should be dexron 6.

 

This gets covered a lot. Search is your friend. See the many varying opinions on this topic below if that's what you're looking for. Note: all of these are less than a year old... Search is your friend:

http://forums.corvetteforum.com/c5-t...id-change.html

http://forums.corvetteforum.com/c5-t...nsmission.html

http://forums.corvetteforum.com/c5-t...-question.html

http://forums.corvetteforum.com/c5-g...-for-a-m6.html

http://forums.corvetteforum.com/c5-g...dy-use-it.html

http://forums.corvetteforum.com/c5-t...ion-fluid.html

So... now you know what GM recommends and you know there are a lot of people on here that don't follow it. Your car, your choice.

 

yep I used the search and read all of the post that came up. I found that the later dated post actually seemed to favor the dexron VI fluid. I was just trying to verify something had changed to allow this fluid in my 99 six speed. I could not confirm that dexron VI is the fluid of choice by GM, so 88861800 is what I plan to use in mine. IF anyone ever can supply GM information that suggest using another lubricant is GM acceptable please PM me the name or P/N of that lube. Thanks

 

FWIW......below is what I used when changing my manual trans fluid at 73k miles. It has shifted like new ever since. I don't road race, and see the strip once a year. I have not lost a wink of sleep, knowing that GM does not recognize Dexron III anymore.....


http://www.valvoline.com/products/co...ssion-fluid/33

 

Thanks for all the replies! To those who suggested doing a search, I did. The problem is half of the people posting don't look to see that it's an early c5. The paper is what is throwing me off. One post says never use mobil1 in early c5's, the next guy says I've used it and it was fine. But when you look at his profile he has a 03. Not really applicable to my situation. What I was trying to get at was other than DexIII what is safe for the paper in my '98? RP Synchromax seems to be solid as well as Amsoil, or DexIV, but, stay away from mobil1.... Correct???

 

I changed to Amsoil ATD a few years ago and have been very happy with it. Over 50K miles with it on my 98 M6. I can't vouch for RP.

 

Why try to "out smart" the GM engineers??

Use GM Manual Transmission Fluid - #88861800

That's what I did and my transmission shifts flawlessly.

No worries here!