Tundra Dweller

Here's comprehensive and non biased test of gear oils for your differentials.
The cold temp. viscosity index was surprising. I used valvoline synthetic in the front and rear diff's.

http://www.lastgreatroadtrip.com/wp-...comparison.pdf

Red Line, Royal Purple and Lucas, having failed the viscosity requirement for SAE 75W, were then tested at the SAE 80W
parameters for comparison purposes. Red Line scored 18,250 cP and Royal Purple scored 24,700 cP, showing better performance
than the SAE 80W-90 gear lubes. Lucas, however, at 98,050 cP, showed worse cold-temperature properties than
Castrol 80W-90, which is reflected in the overall score on page 19.

UtahGuy

Non-biased? It's from Amsoil.

jstockert

And an eight year old Amsoil study.

blupupher

iTrader: (2)

Yeah, I am kind of wondering the point of this post. This was published 8 years ago, was done by Amsoil, and guess which oil tested passed all the tests? Hmm.
Over on BITOG, this test is highly suspect, not that Amsoil is a bad oil, but there are just no specifics on the test samples aside from a lot number. Was it just 1 bottle of each oil tested? Did Amsoil test several of their bottles and just use the best results?
The age of this test pretty much makes it irrelevant. We have no idea what the current formulations of any of these oils are, so no idea what current test results would be. This is also a test on 75/80w-90 oils, only used in the front diff's of 4x4. The rears are spec'ed for synthetic 75w-140, and no comparative tests that I have found have been done.

So the short of it is just use the correct fluid and you will be fine.

Tundra Dweller

Whoops...never mind, carry on.