FormulaTA327

Should the trans fluid be changed after a complete rebuild of a 4l60e. not sure if there is a break in period or not with rebuilds. I have a couple thousand miles on it now and the fluid looks normal

Paul57

I certainly would not use old fluid in a new/rebuilt tranny. And, you will be doing yourself a favor using synthetic but there are a lot of people that still don't comprehend that.

FormulaTA327

i put in all new fluid after the rebuild, i was just wonderin if i should change it again or if it would be ok and just leave it alone. I put DEX/Merc in it

sjsingle1

iTrader: (1)

after my rebuild......i changed fluid after 1000 miles

Gilbert@Ace Racing

Hi Paul... Saw tour comment regarding synthetic fluid and thought I would ask you why you recommend it? Specifically what in your experience makes it a better fluid?

I have been unsing off the shelf house brand atf for many many years with zero issues. I have clients who run very fast, very heavy race cars with the same fluid with sero issues. Now, in some certain race cas I recommend Amsoil air compressor oil because of it's flash temp rating. But thats a safety thing in a non street application.

I have yet to be convinced that a synthetic fluid is worth the added expense. I am open to learning. Can you point me to some data that I havent seen that bolsters your comment? I am all about learning!

g

Paul57

I am not going to get into a big debate about this but will try and share what I know, in this limited space. Most of the more dramatic testimonials and tests come from engine oil or gear lube since they are more popular. It really isn't much different than using conventional (engine) oil vs. synthetic. Conventional will get you by for a long time if changed regularly and most guys will say they never had a problem with the dino oil. But, synthetic protects substantially better (at least twice the life expectancy of components...typically) , keeps internals almost spotless and requires fewer changes. The synthetic molecules (shape, size, durablility etc) are much more suitable for the protection of components than conventional. There is much more to it than this but I am not into all the technical jargon. I have read and heard of (probably) 100's of results that confirm how impressive synthetic is, in any application. I guess the bottom line is...if you are content with mediocre protection then conventional will be fine and your components will wear out as they normally have and look the same (gummed up) internally. If you want the best protection possible which may even cost less in the long run...use synthetic. Since we know heat is a major killer of most fluids I included the attachment. It is the only "public" graph/chart I could find on short notice ragarding ATF. If I wasn't 100% convinced that synthetic was a far superior product then I would not be using it in everything. I am way too $$$ conscious for that. And, no I am not a dealer and I do not make $.01 on anything. Besides...Amsoil is Made in the USA...if you need one more reason. Maybe some others are too??

Gilbert@Ace Racing

Cool. I appreciate your comments. Thanks for taking the time.... Not interested in a debate either, but I do enjoy reading what others have to say and also the documentsthey produce that I may have not seen! :-)

In my experience, which is a long and sordid career in the industry I've found that in automatic transmissions that there is no discernable wear or deterioration of the rotating assembly components when dinosaur fluids are used as opposed to synthetic fluids. I can see the value in using a synthetic fluid in a daily driver such as an SUV or Sedan, even a pick up truck... Basically anything that is not a high performance racing unit. My reasoning is that in a high performance unit we rely on quick and firm shifts in extreme environments. Therefore if we use a "slippery" fluid then the clutches are not going to apply and actually stop the given rotating assembly compenent without some slippage.

That's my armchair quartback .02! thanks for the info!

g

SuperSlow02

iTrader: (16)

I run dex6 in my built th400 per builders recommendation, found it at walmart for 4 bucks a qt. Best of both worlds it seems lol

Paul57

I have heard that before and had to point out that the clutches are held/engaged by pressure and not friction which would make the shift speed and firmness a non-issue. Just another $.02 worth.

SATAN

iTrader: (2)

This would be saying that the type of fluid you use DOES NOT change the amount of friction the clutches generate. That is incorrect. Try using water in your transmission and tell me if the amount of friction the clutches generate is still the same as a nice slippery ATF. That being said, is a synthetic fluid actually more "slippery" than conventional?

I actually came into this thread because I was looking for some good information on syth vs. conventional ATF in a race tranny. So far all I have seen is speculation. I figured it was better to post in here rather than starting a new thread though.

Transmission Specialties told me to run Ford type F in my PL2500 (dunno why ford in a chevy tranny, but whatever). I asked them if I should run synthetic or conventional. They said "Conventional is fine, but synthetic last's longer."

However, I have heard before that there is something in synthetic ATF that will actually cause problems in a racing tranny.

Still no 100% solid info on synthetic vs. conventional ATF though. It is always a "he said, she said" kind of thing.

Paul57

It would seem that you are not understanding what I said and trying to "read into it" too much. Pressure engages and holds the clutches. Friction comes from various things including the split second of slippage from engaging cluthes etc. The type of fluid obviously impacts the amount of friction "eliminated".

Yes

This is right on the money. Synthetic lasts longer and so does your tranny.

That is completely false. If the synthetic fluid is the type rated for that tranny then it is fine.

The chart I posted is not "he said, she said" and I have read of impressive results from several people. I know there are wear tests and other charts available but I don't plan on trying to dig those up anytime soon.

redbird555

iTrader: (14)

Hey Gilbert, I really never believed in synthetic transmission oil either but I did have an experience that really changed my opinion. Few years back my dad had a ford 1 ton truck that he used to tow a lot of bats with usually in excess of weighing 6000lbs.

Of course after years of doing this the tranny started to slip between gears no matter what oil we used it always would have a slipping problem for a few seconds between gears. One day a ford tech recommended switching to castrol synthetic, the tranny took 15 qts so this wasnt a cheap job but instantly after a complete fluid change to synthetic the transmission stopped slipping even when still hauling boats. The temperature of the tranny on the hwy also dropped considerably. After about 20k the fluid would begin to get old and start to slip again but another oil change to synthetic would instantly stop it again.

I should also add that just as an experiment one time we changed back to regular atf and the slipping ensued again almost instantly. So I guess in conclusion there may not be a whole lot of test data from labs or whatever for synthetic atf but when I've seen it for my own eyes i really dont need anymore convincing lol.

I'm not saying that I think it reducers wear in new tranny's or that it's better in racing applications. And hell I dont even use it in my camaro simply because I dont really see a need to and thats its very expensive but i do think it truly is a better fluid.

Dan-