What is used gear oil supposed to look like?

[The Critic]

I drained out a 22k mile old fill of Chevron 80W90 from a highway driven, '92 Toyota Previa minivan last week. As I recall, the fluid did not appear dark brown...I believe it was a bit grayish, and had some other odd colors on it. There was only a touch of shavings on the plug though.

Anyway, what is used gear oil supposed to look like?

 

[Titan]

It depends upon what it looked like when it was new! It's not supposed to be milky, no matter what it looked like new. It's also normal to have paste on the plug. I have found that the higher-quality gear lubes leave less paste on the plug per mile, though.

 

[Whitewolf]

Unless there is something very wrong like the 'milky' appearance mentioned by Titan, or really bad oxidation, the appearance doesn't help much unless you have seen a good number of samples before. Really what you need is a UOA but even then unless you have a VOA or already have that type of information about the formulation then it's difficult. Remember that gear oils are never really very pretty things and they don't smell that good either!

 

[Donald]

Your gear oil (hypoid) should look pretty close to new. maybe you should have it analyzed.