LS WON

Which one is better? Which is your preference and why? This is mainly for the rear end differentials and automatic transmissions as our Corvettes come factory filled with synthetic Mobil One.

Dueysan

I've used Redline gear oils in Subaru transmissions and diffs and it worked well. Was it better than any other synthetic....maybe. They claim it is but who doesn't. All you ever wanted to know about oil and probably some things you didn't want to know is available here:

www.bobistheoilguy.com

jimman

Why tempt fate you really think GM is out to bend you over.

LS WON

CMEPASU

If you're basically stock, minor bolt ons, etc. and don't track the car I would stick with Mobil 1. If you're going super/turbo charging, built motor, racing, etc, then go Redline.

Like it was mentioned above www.bobistheoilguy.com is a great site to educate yourself on oil issues.

Good luck

jimman

curious when was the last time anyone heard of an engine or drive train failure do to poor oil selection.

LS WON

Mobil One makes synthetic auto trans fluid and synthetic 75W/90 differential fluid?

Irv

Engine - never.
Differential - never heard of a failure due to lubricant choice, but some clutch-type limited slip differentials have proven sensitive to fluid formulations with noisiness or lack smoothness on turns. Lots of evidence C5-C6 diffs are like that.
Transmissions - automatics, no. Manuals - yes. Difficult shifting resulting in bent forks, some synchronizer materials being incompatible with some fluids, palpable differences in shift feel in many peoples' opinions (including mine).

Irv

Yes.

LS WON

The cost of a quart is probably less than 8.95 per quart? I would love to see tests between Mobile One, REDLINE, and Amsoil which one fared the best.

C66 Racing

In my opinion, AMSOIL and Redline are going to compare well together. AMSOIL uses a Group IV PAO basestock, the same as the factory fill Mobil 1. Redline uses a Group V ester basestock. I've been more comfortable using a fluid with the same basestock as the factory fill, but with higher additive levels.

AMSOIL doesn't pay to include Redline in its comparison tests as Redline isn't really a competitor of AMSOIL in most markets (though it is in our high performance application). Though not a tranny fluid comparison, you can draw your own conclusions from these AMSOIL commissioned tests:
Comparative Motor Oil Test
Comparative Motor Oil Test Dec 03
AMSOIL vs Mobile 1 Oil Test

CMEPASU

Try this link for Redline products...best prices I've found anywhere with very reasonable shipping www.myoilshop.com

LS WON

I talked to a GM person in charge of licensing and he told me he had not issued a license to REDLINE meeting GM specs on the DEXRON III (H) or now the DEXRON IV for GM automatic transmissions. So is it that GM must give prior authoriziation to which ever synthetic company AMSOIL, REDLINE or Royal Purple in order for these higher end synthetic companies to be able to say they are compatible and meet GM specs? or for you to be safelyl covered under warranty if you use one of these companies products?

LS WON

Good prices but they get you on shipping.

LS WON

thanks for the comparison tests I was looking for something like this as I often wonder if REDLINE, Amsoil are superior to Mobil One or perhaps it really doesn't make a difference and just stick with Mobil One? Mobil One is the lower cost of synthetics and easier to get at most stores Walmart included. Whereas the REDLINE AMSOIL, Royal Purple you have to go out of your way to find them or to a speciality/high end parts store.

LS WON

Simply put who is the best synthetic fluid product? REDLINE, AMSOIL, Royal Purple or MOBILE ONE. These companies have been in existance a very long time especially Mobil One.

StrayDog

Totally agree.................The Dog, woof

su8pack1

What would you be doing that the stock fluids won't work?

rmd8136

Do the Mobil 1 ATF and 75-90 Diff Oil meet GM specs?

Do you need an additive for the diff for limited slip performance even with syntheitc oil?

Two-Lane Blacktop

Is Dextron VI in the A6 a synthetic?