Oldvetter

1997-2000 C5s have paper blocker rings. DO NOT use Mobil 1 ATF, I did and had grinding going into 6th gear after 50,000 miles of running it. I switched to Amsoil ATD and it immediately stopped.

Nobody "ruins" the 6th gear syncros, it is not like I speed shift into 6th gear. It had to be the fluid !

Carcass

It didn't screw mine up-it just didn't shift as well with Mobil 1 as it does now with El-Cheapo Valvoline Dexron 3
It "seems" like it's a little too slippery to let the synchros do their job,but I don't know if that's why it made my Vette shift like an old tractor.
Every since I drained it and refilled with "the cheap stuff",It shifts like a Vette's supposed to shift.
It is possible that the GM folks who made up that little "DexronIII" tag by the fill plug on the tranny knew what they were talking about....

flynhi

Suggest you call Tremec Tech. MN6's through mid 99 were made by Borg Warner and had paper blockers. My Owner's Manual says to use ATF DEXRON III but the techs at Tremec told me to use Mobil 1. Suggest you call them to confirm. There is an old timer from BW now working in the Tremec Tech department.

mlapd

I can see your point, but it also seems like everything nowadays, cars, electronics, etc.... will use the bare minimum to save a buck. Obviously the synthetic costs 2 to 3 times more. Has anyone ever wondered if that is why they didn't use it stock? I had an Infiniti M35 and was proposed a similar question at the dealer. "If the engineers at Nissan wanted a K/N type filter they would have installed it stock on the vehicle". Now we all know that is a line of crap. Same reason alot of the engines and stuff are made to only be serviced at the dealer. The average Joe wouldn't be able to do it. I replaced my wife's spark plugs on her 07 CTS, Holy Sh';/.;t, you had to remove the whole intake manifold just to get to them. Sometimes I think it is more about money than engineering! Just something to think about.

Lap

LT1driver

engineers design with no regard to maintenance folks, same for aircraft...nerds vs mechanics.

itzza427

Per many posts here on the forum,,,,the ONLY synthetic ATF fluids safe for the older C5 M6's(97 through 2000) is Royal purple and Amsoil!! Mobile! and others are reported to ruin the fiber facing on the synchro blocker rings!! later models got carbon fiber facing that work with any fluids.

AU N EGL

Well I will be different

yes I use M1 ATF in the MN6 and M1 Gear oil in the Diff.

2003

AU N EGL

and now dont forget the bean counters.

lets see:
Non direction brake rotors
SS Valves vs Sodium and hollow valves
Steel Valve retainers vs Titanium

helga203

From what i got out of this section is that if you have 97-00 be careful of what oil you put in your m6. If you have newer it's not an issue.

mlapd

So your telling me that when GM tells the engineer's you have this budget to produce this engine or car, they don't take into account of using less exspenive material or fluids in certain areas to save money for other areas that may be more productive or better all around? I find that hard to believe. I am an Aviation Mechanic myself, and you cannot compare aviation to autombiles at all. If something goes wrong on an aircraft, you fall out of the sky. If something goes wrong on a car you pull over. That's another reason aircraft maintenance is so tight on accountability with just about everything unlike most other maintenance. This prinicpal is one reason most of us drive a Vette, because if you can get a car that cost $20,000- $50,000 less than say ie.... a Porsche, but is comparible in performance Why spend the extra $50,000 (If you have it). Obviously, we also love the history and tradition that comes along with owning a vette, but a Porsche is built much better and with alot better materials than the Vettes we own. Same reason a ZR1 is compared to a LAMBO. I'm using this as an example as far as the Porsche/Lambo thing, so lets not start the bashing.

Lap

dbbspider

I didnt want to find out if the Mobil 1 ATF worked on my 99 mn6 (stock tranny) so I just used Castrol Dex domestic multi-vehicle ATF (non synthetic). It works normal, no problems, shifts like stock with over 77K miles on it. FYI, my car is supercharged.

I recommend you use it or any other non synthetic that meets Dex III requirements. If you want to use synthetic, then I recommend using a brand that has no history of paper blocker problems (ie: Amsoil), and call it a day.

http://www.castrol.com/castrol/mispo...ATF282_648.jpg

johnson-rod

I agree.
I read all this 3 years and 65K miles ago and went with Amsoil ATD in my '98 M6.
No problems.
Why risk it?

SaberD

WHAT!?!?!?!?!? I am completely lost here. i thought the paper blocker rings subject had been beaten to death, and we all concluded that 97 to early 01 models did have the paper blocker rings in the m6 transmission. 99% of all reputable sources i have seen state the same thing. The only sources where i have seen conflicting information is from some not so reputable shops.

All synthetic oils cause cellulose compounds to expand. Paper is cellulose. The blocker rings are paper. The blocker rings are cellulose.

Amsoil synthetic ATF or ATD has an additional chemical that makes cellulose compounds contract, therefore counteracting the swelling effect of the synthetic oil, and NOT causing the blocker rings to expand.

Amsoil ATF or ATD is the ONLY synthetic fluid i will use in my pre-2001 m6 transmission that has paper blocker rings.

flynhi

Not to doubt all posters with pesonal experience with this but if using Mobil 1 is such a problem, why do Tremec Tech Reps recommend it?

Oldvetter

I asked the same question of Mobil Engineers, and they said they had heard of no problems with Mobil 1 ATF and early C5s. They should come to this Forum ! I had problems with Mobil 1 and my 1998 C5 MN6 after 50,000 miles running it.

flynhi

I'm at 58,000 miles on my 99 with Mobli 1. What problems did you have with your 98 C5?

SaberD

not all tech reps are reliable resources. i have seen some quotes by many tech reps for many companies that just spit out completely bogus information. They are just that, tech reps. They are not engineers.

We really need to get to the bottom of this.

I spoke with forum member RoadRebel (Dr. Phil), and he is recommended as one of the best corvette mechanics and tuners in the country. He spent 14 or so years as an engineer at GM, and he had the same opinion as me as far as the sythetics/swelling, and amsoil fluid goes. I would trust him over any tech rep. I would also trust a lot of certain forum members here over any tech rep.

Also, from most of the posts i have read since i've been a member here, the damage from using non-amsoil synthetic fluid doesn't show up until around 50k miles later after using the fluid. Just because you notice a difference after first changing the fluid does not mean its good for your car.

MG RED 99

This is what I use as well. No problems in 10,000 miles since changed. It did add a little smoothness back to the shifting feel.

itzza427

It is fine,,,,from 01 on up!!

flynbyu2

Not to detract from the thread, but I'm going with Mobil 1 in my 03 Z06...how much do I need?