# How Much Gain From Synthetic Change



## deputycrawford (Jan 16, 2010)

I have done some searching in the drivetrain section about this but did not find too much specific. 
I would like to change my fluids in my 04 and was wondering if these cars come with Synthetic fluids from the factory, and if not, would I gain much from changing. I read that many people suggest to stick with the factory stuff in the rear end, but should I go to the good stuff in the T-56? 
My cas has 113,000 miles on it and I really want to change everything in the spring. No problem going with the Mobil 1 in the crankcase, but is synthetic brake fluid any better for the clutch slave? Should I expect any difference in trans shifting? I will search some more but was hoping someone could put an answer together all in one post. Thanks

Jerry


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## GM4life (Mar 18, 2007)

I haven't done test myself, saw an ep. on Horsepower TV one day, they dynoed a 4th gen Camaro SS I think with factory fill oil, tranny, diff. Then they changed out all of the fluids with Royal Purple ran it on the dyno and gaind some power. Our 04 GTO comes with the standard oil non-synthetic, ATF tranny and synthetic diff fluids.

I changed my engine oil to Mobil 1 the first day I got it and been running it every since. Currently I run Dextron VI synthetic in the tranny without any problems. And stock diff fluid that my second diff came with. I might change it out to the latest and greatest from GM or go back to Royal Purple in the diff. If I were you I would stick with the standard DOT 4 brake fluid or fluid that is compatable with ABS and our brakes. I use ATE Superblue brake fluid in my brakes and clutch.


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## deputycrawford (Jan 16, 2010)

Ok guys, I might have jumped the gun. I changed my search parameters and found one post says synthetic fluid in the 6M causes the syncros problems and can be too slippery. Another post mentions rear end fluid should be factory because syth can either cause chatter or one wheelie peelies. I have yet to find much on the brakes and clutch slave. I would guess to keep it factory and I will ensure consistant performance. I guess I'm just gonna have to sit in front of this thing a little longer. 

Jerry


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## heyman (Jan 15, 2010)

I'm an Amsoil dealer, and have used it in everything, and I mean everything, as far as power gain, not what you think, but it does for sure make things move easier, Change all the fluids in my 78 Chevy 4x4 , and the difference in cold weather was big, own this truck from new, in sub zero weather still starts like it was summer, and was alot lighter on it feet, like in rolling resistance, original battery had lasted 11 years.


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## Vetterss (Feb 2, 2010)

*rear end*

They come with synthetic from the factory. Very expensive as well. Doing mine in a week or two. Heard that from a long term GM mechanic and it even says that in the service manuals.


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## jpalamar (Jul 22, 2008)

I'm running RP w/ syncromesh in my trans it it shifts smooth. It is thinker then the stock stuff so on cold starts it sucks but once warm I feel it shifts much better. I'm also running RW 75w140 in the rear with no issues. As far as engine oil, I just buy whatever is on sale as I've never noticed any difference in motor oil since I change my oil regularly anyway.


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