Recommended Brand of Gear oil Amsoil or Redline?

[bluestream1]

I am going to change my rear differential oil, and would like to know if Amsoil or Redline is the preferred brand. I would probably use Mobil 1, but it is twice the price of the other two.

Also, my owners manual is contradictory on what weight of fluid to use. On one page it states that “all conventional differentials should use regular gear oil”, and on another page it states “that all differentials with 3:73, or 4:11 gear ratios should use synthetic oil”

I have a conventional axel (code 42) with 4:11 gears

 

[jimbo74]

ok here is the reason and you will need to look it up

either synthetic will be fine

some synthetics already come with a friction modifier for use in limited slips, some do not and it needs to be added


with your gears and open diff, you have no issue, running any of the above 3 just as they are, straight from the bottle

in your case i would buy whatever is cheaper, they are all high quality oils

 

[aldive]

I personally recommend and use Amsoil Severe Gear 75w90 oil in my 3.73 LS differential.

Dead Link Removed

 

[bluestream1]

I emailed Amsoil and this was their reply: Select either 75W110 or 75W140 AMSOIL Severe Gear Oil for this differential.

Does anyone know which weight oil comes as factory fill? I am leaning towrds the 75W110 for fuel ecomony, but I don't want to go thinner than the factory lube, as I have 175,00KM on this truck...

 

[aldive]

75w140

 

[IZwack]

I am leaning twords the 75W110 for fuel ecomony

You wont notice any gain by switching different differential gear oil.

 

[aldive]

You wont notice any gain by switching different differential gear oil.

I noticed a mileage difference, albeit small, when switching from 75w140 to 75w90 ( all Amsoil ).