Off the shelf synthetic GL5 gear oil, differences?

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Thinking about doing a rear differential change and from what I heard I should use a good 75w90 instead of the 75w85 that Toyota / Lexus wanted me to use. Seems like most if not all 75w90 are synthetic and Mobil1, Castrol, Valvoline are the easiest to find in the store, and M1 / Valvoline are the same price (cheaper than Castrol), I'm debating whether to use M1 or Valvoline.

Seems like based on Amsoil's "test" M1 is thinner new but isn't passing some of the MIL spec that Valvoline passes. I personally prefer a thinner oil because it is closer to the manufacture's original spec, would those extra MIL spec really mean anything if my car isn't requesting it?

How different are gear oil between brands for the same price / visc / etc?
 
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Hi,
PandaBear - I have done extensive testing (millions of Kms and a hundred or so UOAs) of Mobil (Delvac) and Castrol's synthetic 75W-90 gear lubricants - both performed almost identically

This was shown and tear down inspect time and in component (seals/bearings) longevity
 
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Originally Posted By: PandaBear
Thinking about doing a rear differential change and from what I heard I should use a good 75w90 instead of the 75w85 that Toyota / Lexus wanted me to use.


Are you sure about the 75W85?

The Toyota I have specifies 80W90 below 0F and SAE 90 over 0F for rear diff and transfer case.
 
PandaBear is correct. My 2011 Tundra specs 75W-85 in the front and rear differentials. The only one I am aware of is RedLine's 75W-85 Gear Oil.

I ended up using Amsoil's SVG 75W-90 in mine.
 
Originally Posted By: friendly_jacek
Interesting. Is this the same hardware as the previous years that was back speced from 80W90 to 75W85 for fuel conservation?


It seems like the additive technologies have improved that it warrant the change.
Lubrizol TowProof
 
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Originally Posted By: PandaBear
Originally Posted By: friendly_jacek
Interesting. Is this the same hardware as the previous years that was back speced from 80W90 to 75W85 for fuel conservation?


It seems like the additive technologies have improved that it warrant the change.
Lubrizol TowProof
Good read. However, why are you looking for the 75W90 then?
 
Originally Posted By: friendly_jacek
Good read. However, why are you looking for the 75W90 then?


It is cheaper to buy an off the shelf 75w90 synthetic than 75w85 (don't want to mail order).
 
Originally Posted By: PandaBear
Thinking about doing a rear differential change and from what I heard I should use a good 75w90 instead of the 75w85 that Toyota / Lexus wanted me to use. Seems like most if not all 75w90 are synthetic and Mobil1, Castrol, Valvoline are the easiest to find in the store, and M1 / Valvoline are the same price (cheaper than Castrol), I'm debating whether to use M1 or Valvoline.

Seems like based on Amsoil's "test" M1 is thinner new but isn't passing some of the MIL spec that Valvoline passes. I personally prefer a thinner oil because it is closer to the manufacture's original spec, would those extra MIL spec really mean anything if my car isn't requesting it?

How different are gear oil between brands for the same price / visc / etc?



I have Amsoil Severe Gear in my transfer,and rear diff. Works for me.
 
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