Thread: What Tranny Fluid should I run?

I'll be installing my Built Tranny next month. What fluid do you guys recommend? I've heard stay away from synthetic.

I've used Valvoline Max Life on my tranny since I got it and it seems to have always worked good. I'm thinking I should run a different fluid though since Max Life is for higher mileage trannys.

Also the new tranny will have a 3,000 stall so i'll image there could be more heat with that stall.

My GT has Max life in it...for high mileage...

My GTP has DexronVI from ZZP.

Trannyman...what do you use?

Ive run synthetic fluid in my transmissions for 15+ years now. I did a complete flush on the GTP right after I got it. That said, I think Trannyman has WAY more expertise in this area than I and he has proven experience so whatever he has to say would probably trump my input.

Trannyman uses a 'special blend' of his own. Not sure whats in it...I don't want to know.

But I would recommend getting a good quality Dexron VI fluid. If it were me, I would go with Valvoline because it is synthetic and meets the Dexron VI specs. Not many fluids do this and I consider this to be one of the best.

You shouldn't have any problem running a synthetic trans fluid and it will only help you in the long run.

yep Trannyman mixes his own. And no he doesn't say what it is. He did my transmission work so whatever he used will stay in there for the life of the fluid. Without access to the special blend, as Zef mentioned, I'd use Dexron 6.

I dont have anything to hide You just have to buy it in 5 GALLON buckets lol. Since most people have no reason to buy that much fluid there isnt much point to talk about it unless you want to use it. I have no experience with Dex 6 and am happy with what i have used the last 10 years and dont plan to change, but a lot of people use it and it works fine though it is pretty pricey. With a 3K stall converter I would strongly suggest to run an external cooler hands down. Heat kills transmissions no matter what fluid you use and a higher stall adds more heat.

Lets see. Transmission holds 14quarts. Do a complete flush and you'd want to have a couple spare quarts just to be sure you got all the other stuff out, so theres 16 or so quarts. Just a tick over three gallons. Service time comes up you can just drop the pan to buy some time until you can flush it again, that holds about 6 - 7 quarts. So yeah, I could do a 5-Gallon bucket.

I cant imagine what shipping would be, but with your proven track record I could go for it.

I mix it 5-6 quarts and the rest dexron 3, so after 4 fluid changes you have used a whole bucket! I recommend every 25K to 30K miles for fluid changes, so if you plan to keep your car that long then it may work out. Most people never change the fluid that often though and ends up around 50K miles. On my old 95 prix with an L67 swap it ran high 12s and it had hundreds of track passes, the majority with drag radials or slicks, and when I sold the car the trans had 35K on it and I serviced it before I sold the car and the pan was spotless and the fluid still looked like the day I put it in. I also used a larger external cooler. That car was raced near every weekend at the track and on the street and had a lot of hard high speed run miles on it. The fluid works, but again a cooler is important. My trans temps were always around 150-170 year round.

Trannyman, you have any pics of your cooler set up? I have always been adamant about keeping tranny fluid temps low because I too was taught early on that heat is the death of a tranny so I have had an external cooler on every car I could put one one and on my last one I use an external filter to boot just for that added filtration and a little extra fluid capacity.

The coolers I use I sell on my website for $50 and have a 26K gvw rating. I have been using them for a long time and have always had great results. I dont like using the factory cooler in the radiator on most high perf cars with higher stall converters as often the trans will run cooler than the radiator will, and you dont have to worry about the risk of the cooler going bad in the radiator and contaminating the trans with antifreeze which will ruin it in a short matter of time. They just mount in front of the condensor with plastic push through zip ties. Most guys always want to argue that stacked plate coolers are better, and I wont argue that but the cost is normally much higher and as many of these coolers that I have installed and used on my own vehicles I dont worry about it and have never had one not work good enough.

I wish someone made a fully bolt on tranny cooler kit with proper fittings. Even the GM Cooler and the MSP Desert fox coolers had hosed clamped lines which bother me. I haven't found a kit yet that I like, thats why i've never bought one.

Still not 1000% sure what fluid to run....

Shawn, Ive been running the GMPP cooler now for probably two years with no problems. I got a double flaring kit for the hard lines, clamped on the rubber lines and its been golden ever since.

So what you are saying is that someone needs to offer a true BOLT-IN cooler kit with no clamp on lines?

Uh oh, I feel a 'I have a solution moment' about to hit.

LOL now why would you have one of those again???

Well I actually meant that I was expecting it from you but I worded it all screwy so the punch has been lost, LOL.

I know what you meant, I caught it I just went to 3800performance.com and they sell the MSP cooler. It is $239.99 which is a chunk of change to throw down on a cooler, it looks like half of the cost is the lines and fittings. I dont understand why all of these coolers still route through the factory cooler. Sure it has its place, but you are buying an external cooler for a reason, it isnt to just marginally or try to help keep the fluid cooler, that IS the reason you bought it and with any high performance car that gets driven hard you need cooling that works well. Adding an external cooler will add capacity to the system, but my whole point is always why heat the fluid up to cool it back down? Running it through the radiator will certainly help heat the fluid up quicker but with fully electronic controlled transmissions and the advancements in fluid over the years i dont see the concern for this. When your stock cooler in the radiator gets a hole in it you are screwed and possibly trash your whole trans, or because of the design debris will collect inside and cause a restriction to further the damage to the new trans getting installed. Last weekend when we went up to the Detroit auto show we road up with a friend that just bought a new 08 GMC full size dually, 3500 I think, but it has the Duramax diesel and the Allison 5 speed auto. The dash lets you scroll through some engine data and trans temp. After 3 straight hours of driving the trans temp was all the way up to 115 deg F, yes that is NOT a typo! I couldnt believe it. They must use one killer trans cooler on those! But that just proves another point about the fluid not being warm enough causing problems, this is a factory vehicle and brand new at that with extremely low trans temps, they want it to last

Well that blows what Ive been told then. I was told I think shortly after getting my GP and when I was looking for a cooler that if the fluid wasnt up to 140* or something like that then the computer would disable overdrive.

Doesnt make a lot of sense to me, but thats what I was told.

With regards to the Duramx, yeah 115* after three hours of driving, that is some dang fine cooling there.