rear differential fluid
- Thread starter mikeyy
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I would run 80W-90, I think 75W-90 is a little thin...
GL4 and GL5 gear oils have different properties and are not sequentially #'d the same way as transmission fluid, (i.e. Dexron V is newer and better than Dexron IV). I'd stick with the GL rating if I were you. The ratings indicate the use of the oil. That said, there are some oils that appear to provide protection for both GL4 & GL5 specified uses - AMSOIL appears to be one of those (if you believe their marketing).
Cruiserdrew
On the way there
As long as it's GL-5, it will be OK.
GL-4 does not meet the spec, so don't use it. that's for transmissions and transfer cases and similar.
Whether it is synthetic or conventional will not matter.
GL-4 does not meet the spec, so don't use it. that's for transmissions and transfer cases and similar.
Whether it is synthetic or conventional will not matter.
There is not much difference between 75W and 80W. And once at operating temperature, both 75w90 and 80w90 will flow at 90w.
I run Amsoil Severe Gear Oil 75w90 in my rear and front diff and transfer case with no issues.
I am running 75W/90 in my front, rear and trans case.
No issues.
75W and 80W is just when its cold. 75W is going to flow easier if your in a cooler climate. Its not really going to make a difference. At temp its going to be 90W.
So it just flows easier when cold. At temp its the same.
No issues.
75W and 80W is just when its cold. 75W is going to flow easier if your in a cooler climate. Its not really going to make a difference. At temp its going to be 90W.
So it just flows easier when cold. At temp its the same.
I have 75W90 Redline in front/transfer/rear with no issues... I bought it straight from their site and its GL-5 don't recall seeing them selling GL-4 ? Though it might be on there somewhere but not in their Diff/Gear Oil category.
I would agree with the above comments... stick with GL-5
Here is a quote from the Mobil 1 website that explains how these fluids are not interchangeable.
API GL-5 gear oils can be acceptable for differentials but generally are not recommended for transmissions because a GL-5 gear oil has twice as much Extreme Pressure additive for GL-5 quality gear protection. Even though this Extreme Pressure additive is good for gears it can be aggressive and cause corrosion on the soft yellow metals (brass, copper, bronze) found in the bushings, etc. in manual transmissions (in these applications a GL-4 product is usually specified)
Here is a quote from the Mobil 1 website that explains how these fluids are not interchangeable.
API GL-5 gear oils can be acceptable for differentials but generally are not recommended for transmissions because a GL-5 gear oil has twice as much Extreme Pressure additive for GL-5 quality gear protection. Even though this Extreme Pressure additive is good for gears it can be aggressive and cause corrosion on the soft yellow metals (brass, copper, bronze) found in the bushings, etc. in manual transmissions (in these applications a GL-4 product is usually specified)
OK, so should those of us with ARB AirLockers be concerned, as the pressure lines in the diff are copper? Currently running Mobil 1 syn 75w90 which is GL-5.
Steve
Cruiserdrew
On the way there
OK, so should those of us with ARB AirLockers be concerned, as the pressure lines in the diff are copper? Currently running Mobil 1 syn 75w90 which is GL-5.
Steve
No-Modern gear oils are buffered and the "harm to yellow metals" thing is no longer a concern.
Besides, with rare and very expensive exceptions, GL-4 is not available, and you can't run it in a diff with Hypoid gearing.
That 75w-90 is great stuff and will give excellent service.
Cruiserdrew
On the way there
Just as a for instance, the FJ60 owners manual even specifies GL5 for the transmission. It is not something you need to loose any sleep over.
BTW-GL4 technically does not exist at all. The secification is obsolete.