We talk all the time of what kind of fluid to use in racing transmissions. But i wanted to make a post of what we have found this year in both, my farm team of race cars, and my O.E. rebuilds and reman transmission we do in my shop. Modern day cars are using HIGH stall converters to help an engine that is making 150 hp accelerate a 3500lb car like its got 300 hp. They are also cycling and pulsing the lock up on the converters. Both is very hard on the converters, transmission, and transmission temps. For most cars that we rebuild the transmissions in, we use a generic synthetic, bulk transmission fluid that "works" with most transmissions on the road today, if you were to buy something like this off the shelf, you would spend 5-7 bucks a quart. The stuff works as it should and without issues, but does break down fairly quick. It is not uncommon for this particular fluid to start losing its "red" color after 25,000 miles in chevy applications, and 40000-50000 in fords and chryslers. Understand, chevy/gm does things a little more fooked than the other manufactors and in turn, is harder on the transmissions. On cars 2010 and newer that have 6 or more forward gears, we started using o.e. fluids, (Mercon LV, and Mobile 1 Dex VI) and have seen that the fluid is staying red longer, and we do not see converter shudder issues like we do from the generic fluid and we see lower temps.
My farm team has been using the generic fluid that i have provided for several seasons now. The only complaint about the fluid has been, that reaction times start varying a bunch at, or around 50-60 passes. At the same time, the fluid would start showing, and holding more temperature. Change the fluid and everything went back to normal. So this summer I had my team switch to Mobil 1 dextron VI. At 100 passes, these guys hadnt noticed any reaction time or temp issues to be worried about. 1 of the guys made 200+ passes on his with same mobil 1 fluid, and its still as red as it was when he poured it in. The other guys were used to changing the fluid at 50, so they just changed it at 100 passes, and didnt see ANY difference.
One of my guys uses transynd 295 and 668, he HAD to switch to it because trans temps he sees. But he has a 3400lb truck, twin turbo 400 sbc that run 490s/5.0s and he litterally has pulled back into the pits at 260 degrees. And in turn, he has to change the transynd around 20-30 passes because of heat break down.

Here is the point of this long read. We all have alot of money in our stuff, and we EXPECT it to work flawlessly and consistently through a very wide range of conditions. Just know, that IF you cheap out on transmission fluids, you WILL have to service the transmission more often to maintain a level of consistency. My suggestion at the least, is to go to your local GM dealer and buy the mobil 1 dexton VI fluid. Its always in stock, and list price on it is 9.60 a quart. In my opinion, that is a very good price for a fluid that will work for MOST guys out there on this forum. If you are not tight with money, then my suggestion would be to move up to the transynd fluid. It will cost you 40+ a gallon, but it is worth it. Now, if you are in a unique situation that you have to run a heavy fluid, like compressor oil or hydraulic oil, than use the BEST you can buy. You just have to remember that those 2 oils are not designed for clutches or clutch engagement. Yes, for no more than we use these fluids you will most likely never notice anything other than having to replace band and clutches more often because of the lack of shift modifiers in the fluid.

Also, Rural King/Tractor Supply brand "transmission fluid" is some of worst bull **** out there and should not even be in your daily driver. In our tests, it was even worse than the bulk fluid I buy and would start showing inconsistencies on the 2nd night of racing. Change the fluid and it would come back.

So what are your thoughts on the differences between the Castrol Transynd 295 and 668?
It states 668 has improved additive package, so what the hell does that mean and how would it affect a racing transmission if at all?

quote:

Originally posted by Big Steve:
So what are your thoughts on the differences between the Castrol Transynd 295 and 668?
It states 668 has improved additive package, so what the hell does that mean and how would it affect a racing transmission if at all?

Didnt see any difference on timeslip or data logger. Ive been told the 668 is a little better in colder weather, so that COULD mean that its a little thinner, OR just has a different lubricity factor.

Steve, understand that both the original and the “new, better, improved” version of Transynd were designed for extended use on fleet vehicles, not our race car transmissions. That said the only benefit to using Transynd in race transmissions is the fact that it doesn’t loose viscosity under high load, high heat, same as any full synthetic trans fluid.

Bottom line is you choose to either run cheap conventional, dinosaur fluid/oil or you chose to run more expensive synthetic fluid/oil.

I chose to run synthetic oil/fluids and have been for decades in my engines, transmissions and rears along with synthetic grease too where applicable. Before I started using transynd, I used both Mobil 1 and ATI/Joe Gibbs synthetic trans fluid and I change it every season. Haven’t burnt the trans fluid in any race car since 2005, foot braked, doubled enter and in the late rounds on both, when I ran Type F conventional trans fluid.

This message has been edited. Last edited by: 1320racer,

quote:

Originally posted by 1320racer:
Steve, understand that both the original and the new and the “new, better, improved” version of Transynd were designed for extended use on fleet vehicles, not our race car transmissions. That said the only benefit to using Transynd in race transmissions is the fact that it doesn’t loose viscosity under high load, high heat, sane as any full synthetic trans fluid.

Bottom line is you choose to either run cheap conventional, dinosaur fluid/oil or you chose to run more expensive synthetic fluid/oil.

I chose to run synthetic oil/fluids and have been for decades, engine, trans and rear along with synthetic grease too where applicable.

This is dead on. The one thing i noticed in my dragster with the cheap/bulk trans fluid is that anything over 180 degrees and i would start losing converter efficiency on the big end of the track. It would start falling back on the shift higher by about 50-75 rpm, but would lose mph in the 660', et would be the same. When i switched to the mobil 1 it wasnt NEARLY as bad, and the the transynd, even at 200 degrees would still be the same as when transmission was 140 degrees.

We rarely see 200 degree trans fluid in my cars .

After switching to TD I burned up just about every fluid I ran before finally trying Transynd, thanks to Ed, I will never run anything else going forward. Just trying to understand the difference between the 295 and 668. I still have 3 gallons of 295 on hand but my supplier the Dmax store is now only showing the 668 in stock and wondering if Castrol is going to phase out the 295 completely

quote:

Originally posted by 1320racer:
We rarely see 200 degree trans fluid in my cars .

I normally dont either, but at the Turkey Race at Bowling green i was doubled at 7 cars, lost 1 then lost my other at 4 cars. I would turn off the track at 210, and then be back to 175 by the time i drove back to the trailer to splash with fuel and go back up. That is with dex vi, and i fully agree that with transynd it would have been 15-20 degrees cooler, and i KNOW that is fact because we have made that change on several vehichles that we couldnt get the temp under control.

Agreed, I have seen a 20 degree reduction in trans fluid temp too.

What do you guys attribute the lower temperatures to? What property of the fluid translates into lower temps?

quote:

Originally posted by Bucky:
What do you guys attribute the lower temperatures to? What property of the fluid translates into lower temps?

Purely the additive package. Most ALL transmission fluid starts off with same base stock.

quote:

Originally posted by 329L:

quote:

Originally posted by Big Steve:
So what are your thoughts on the differences between the Castrol Transynd 295 and 668?
It states 668 has improved additive package, so what the hell does that mean and how would it affect a racing transmission if at all?

Didnt see any difference on timeslip or data logger. Ive been told the 668 is a little better in colder weather, so that COULD mean that its a little thinner, OR just has a different lubricity factor.

Did you mix the 2?

quote:

Originally posted by Big Steve:

quote:

Originally posted by 329L:

quote:

Originally posted by Big Steve:
So what are your thoughts on the differences between the Castrol Transynd 295 and 668?
It states 668 has improved additive package, so what the hell does that mean and how would it affect a racing transmission if at all?

Didnt see any difference on timeslip or data logger. Ive been told the 668 is a little better in colder weather, so that COULD mean that its a little thinner, OR just has a different lubricity factor.

Did you mix the 2?

Im sure a little was mixed. We did drop the pan and filter, and let it drain for a couple hours, but i am sure there was some still in converter.

We need a fluids specialist on the forum.....it's like metal properties a little of this, a little of that affect strength,elasticity, ductility, hardness ect.....that's why there are pages and pages of alloys.....what was added and how does it affect the performance. I doubt we will.....but it would be nice to get schooled on different additives. I think everyone appreciates the real world experience being shared.....thank you. Would love to know some of the science behind it.

I couldn’t care less about the science, I tried it 16 years ago after speaking to the chief engineer who developed it. My trans temp dropped 20 degrees and I have yet to burn the fluid since then in any of my race transmissions. SOLD, no reason to try anything else nor any reason to try the new and improved version unless they stop making the original 295.

Every new Allison, from Allison now "Comes" with the 668. My Older 4R100 in the dually with a triple disc converter. Trans temp dropped 18 degrees. Truck has a HD cooler also. 7.3 turbo.
Had some minor seepage from a new front pump seal when it got hot towing the box. This is years ago.
Not a drop after the 295. It just plain works.
You think Allison wants these massive transmissions back in for warranty work from garbage fluid?. If it can protect 80K Lbs every day, all day. It is the best insurance for my midget PG.

Nice little bench job on a 3000. lol....

https://www.youtube.com/watch?v=O3nC4zCXsbA

This message has been edited. Last edited by: TD3550,

What are the thoughts on Royal Purple or Mobil-1 synthetics?

quote:

Originally posted by HR3377:
What are the thoughts on Royal Purple or Mobil-1 synthetics?

Mobil 1 dex 6 is what my final test was and out performed everything besides transynd. Royal purple synthetic is a not a bad choice, but is more expensive than Mobil 1 dex 6 and is roughly same price as transynd, and not as good as transynd either. Shaeffers makes a couple good synthetic transmission fluids that are good, but again, the price is more expensive than transynd. Transynd broke down is going to cost 10-12 bucks a quart.

quote:

Originally posted by 1320racer:
I couldn’t care less about the science, I tried it 16 years ago after speaking to the chief engineer who developed it. My trans temp dropped 20 degrees and I have yet to burn the fluid since then in any of my race transmissions. SOLD, no reason to try anything else nor any reason to try the new and improved version unless they stop making the original 295.

That's nice. I appreciated the recommendation on this fluid. I really was sold when Big Steve made his comment that it was the only fluid that never let him down. I like to know WHY things work. If you don't that's fine....no problem. Thanks again to you and others for the recommendations

quote:

Originally posted by TD3550:


Nice little bench job on a 3000. lol....

https://www.youtube.com/watch?v=O3nC4zCXsbA

That was a neat watch! He made that look easy!