I just got a 89 Camaro IROC-Z, 350 TPI with a 700-R4... 65 000 original miles and all stock before removed AC.

Do you guys recommend using synthetic oil for the transmission or I should buy regular oil like they recommended when it was new?

I want to change the oil in the rear end too, can I go synthetic or not?

Thanks!

 

Sure, you can change to synthetic. I pesonally think it's worth it. I've been running Mobil-1 Dex oil in my S10, and tow a 17' boat pretty often. Not a glitch and 64K on the odometer now. That's w/o a external trans oi cooler too.

I figure if you can cut down on friction, it stays cooler and lasts longer. Heat kills auto trannys.

 

Any other opinions about that?

What about the rear, can I use synthetic for it too? Mine is POSI by the way...

 

Yeah, synthetic for the rear end too. You could also change to syn. motor oil, bearing grease etc...

If you're looking for opinions on synthetic vs. dino oil, it's been beaten to death already.

 

You may or may not be able to use the syn in the rear.

Some posi's are very picky when it comes to oil, you may have to revert back to a mineral oil if it acts up.

Just make sure you go down to GM and get the fancy little bottle of additive (bring the vaseline, it wont be too cheap)

 

Well I think i'll use Synthetic in my engine only for now then.

Thanks!

 

I've been using Mobil 1 in the engine, tranny, and rear end (with GM additive) for several years. Recommended.

JamesC

 

Watch synthetics in the rear if u do a lot of drag racing.

They dont have near the "hypoid tension?" I believe is the term that the dino fluids do.

Basically dont absorb the shock between the ring and pinion as well as the dino fluids.

later
Jeremy

 

Okay, I'll use synthetic in the transmission too but not in the rear. And I'll be sure to buy the GM additive for the POSI.

 

I believe it's called "EP" rating, as in Extreme Pressure. There should be something written on the label advising if the oil is rated "EP".

Higher quality synthetic diff/tranny oils will inform you. My personal experience I have found Red Line synth. oils to be the best!

 

after buildin and playing with several 700R4's, I HIGHLY reccomend staying away from sythetics. I've had two trannies, the first of which I took out and tore back down, that had slippage issues simply because of the sythetic fluid. The 1st was in a V8 S10(built motor, juice, 3.73 gear), the 2nd was in a 4x4 toy(built 350 vortec TPI, 3.73 gears). The S truck started slipping and I ripped it back out only to find nothing wrong. I checked EVERYTHING over several times before putting it back together and putting regular dexron III back in. No problems since. - The 4x started slipping and I simply drained the sythetic and went to regular dexron III and that was about 10k VERY hard miles ago, no problems since.
- I think the stuff's just too slick for the clutches to grab right. That's my theory anyway...I just know that the fluid is all I changed to fix the problem.

 

An interesting note, Moser used to (probably still does, haven't ordered a rearend in a while) refuse to warranty any rearend that ran synthetic fluid. Since then, I have only run high quality petroleum based oils for the rear.