deejbee

I am going to get the transmission fluid changed in my 1999 M6.

Dealership said they are going to used Dexron 6 in it.
I asked if it was backwards compatible with Dexron 3.
She insisted that it was and that is what they use.

So who is right? Corvette forum or parts counter employee?

I have part number 88861800 as the proper fluid to use in my transmission.

Pounder

It MUST be NON SYNTHETIC ATF for the early T-56 Trans !!!!!

terrywerst

Why question her advice? She does this daily...

deejbee

Because I would rather be sure her advice is right as opposed to the possibility of having to replace my transmission if it is wrong.

Not that a dealership would be incorrect about something.

jackthelad

She is dead wrong!! Dex VI is ONLY backwards compatible for auto transmissions. Here is a sample GM bulletin, they issued a whole batch of them for their different vehicle brands.

Especially note the part about not using Dexron VI is any manual transmission, or failure may occur:

Document ID# 1897292

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Subject:Manual Transmission Fluid Usage In 2007 And Prior Manual Transmissions And Transfer Cases - keywords case fluid manual transmission transfer #PIP3836B - (02/05/2007)


This PI is superseded to add a note under concerns. Please discard PIP3836A.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:

Use of manual transmission fluid part number 88861800 U.S. (88861801 Canada) in place of Dexron III.

Important Note: If the vehicle owners manual lists Dexron VI as the recommended transmission, transaxle or transfer case fluid disregard any information supplied in this PI. Use eSI and or the vehicle owners manual to determine what type of fluid should be used prior to referencing the below information

Recommendation/Instructions:

Manual Transmission fluid part number 88861800 U.S. (88861801 Canada) is currently available through GMSPO. Current and past model vehicles listed above with either a manual transmission or transfer case that REQUIRE Dexron III should use the above listed manual transmission fluid. This fluid is a direct replacement for Dexron III in manual transmissions and transfer cases. DO NOT use Dexron VI in place of the manual transmission fluid in any manual transmissions or transfer cases as a failure may result.

------------

In short Dex VI will fry your manual transmission. The dealer should use the referenced Manual Transmission fluid. Alternates are fluids designed for 2007 and earlier vehicles where Dex III was originally specified. Basically, they adhere to the old Dex III spec. I am running Valvoline Dex/Merc, plenty of Dex III compatible options out there.

Christian327

Genuine GM Fluid 88861800 Manual Transmission Fluid is what I used on my 99. The only other brand of fluid I might try with the paper blockers is Amsoil.

Corvette#2

That's the correct fluid. I used it last year in my '00.

CF is right, dealer is wrong.

jackthelad

Any other brand of fluid is fine, as long as it's not a synthetic, and meets the spec for 2007 and earlier GM vehicles - i.e. Dex III, except that GM has withdrawn the use of that name, so you see the reference to earlier vehicles on the containers.

Factory fill was a straight, non synthetic Dex III, as is GM 88861800.

burneyr

Used GM Manual Transmission Fluid in my '00 as recommended by the bulletin. Dealer did not have it in stock, but had it the next day.

deejbee

Everyone, thanks for the posts.

I am glad I asked about this here as I wasn't sure. I am taking my car in for an oil change and transmission fluid flush in a few weeks and was kind of "prepping" in advance.

I can't fault the counter person for being wrong - mistakes are made. But when I questioned her - and I was being polite - she got indignant towards me. Wasn't too happy about that.

I think I am going to contact a bunch of stealerships and ask what transmission fluid they use. First right answer wins my biz!

don37

Astounding you got such bad info from that dealer employee.....

memmer

She would hear from me if only to inform her about this before she costs someone a lot of grief.
Fred

deejbee

All right. Wrote to a handful of GM dealer service departments. 3 got back to me.
All three said they would use Dexron VI in my transmission.

I think I will just buy the right stuff myself and take it to a shop and get them to change it instead of the dealership. I didn't think GM service dept's would be batting 100% getting it wrong. Doesn't give me a warm fuzzy feeling inside.

I was hoping ONE would get it right. Still waiting on a few more to respond.

And one of the dealerships that responded saying they would use Dexron VI is probably one of the biggest Corvette dealers in Canada. Wow.

jackthelad

The front desk person on Service is rarely technical and probably knows nothing about manual transmissions - along with the majority of drivers in general.....

Best to tell them exactly what fluids to put in, otherwise you are hoping that the oil change person (again, not a proper technician) knows what to do.

Someone else reported on this forum a while back that the dealer had used Dex VI in their M6 - and had to get it done over with the proper fluid.

don37

Wow. Awful. Obviously the service bulletin needs to be re-posted by GM to their dealers.........

jackthelad

Deejbee: I would write to GM Canada and tell them their dealers are not following their bulletins, which could lead to them having to replace transmissions at their expense.

Corvette#2

I wouldn't flush the transmission. Just drain and refill it. Maybe that's what you meant.

I've read of people getting systems contaminated because of dirty fluid leftover from someone else's flush being left inside the machine. I guess the EPA regs are pretty tight, so they don't clean them out after every flush.

deejbee

Actually I think I am going to.
I usually give people the benefit of the doubt but counting the dealership yesterday that is 4/4 that said they will put Dexron VI in it.

deejbee

I worded it wrong. I am going to get a drain/fill. No flush.

I did that a few years ago on our Honda Civic and it ruined the transmission. Heard of it happening, didn't think it would happen to me. But it did.

racebum