diff oil color

[JHZR2]

Hi,

What would diff oil from a diff thats on its 'way out' look like?

Similarly, what would it mean if a car's diff oil looked murky, kind of like muddy water (or muddy oil)?

If I filled the diff with redline, what should my drain interval be so that I can hopefully clean the diff and remove the oil before it is too contaminated?

Thanks very much,

JMH

 

[Chris B.]

I just changed my 2003 Silverado differential oil out and it had 7,600 miles on it. It was dark gray and the magnet did have a little bit of metal on it but it didn't seem like much.

 

[widman]

grey or white-ish is usually water. a drop of the oil on a hot surface (aluminum ash tray over lighter) will indicate water as it pops. most other color either comes from the base oil or the additives.
About the only way to know that it is losing it's ability to protect is to look at the gears for signs of no sulfur-phos sacrificial black coating.
Other signs would be heavier viscosity, either by oxidation or dirt.
Most differencials oils are changed earlier than otherwise could be by dirt contamination. Best way to avoid that is run a breather hose up to the engine compartment somewhere that water can't get to it.

 

[Mike_dup1]

GM diff's already have breather hose. But often owners have the vehicles rust-proofed and the coating may end up covering these up. Also they should be checked when the vehicle is service for oil and filters to make sure they are working properly. Most owners and quick lube places don't even know these exist. A dealer would and should be looking at this for you.