just changed my front diff to find it was a gray color??? truck is an o3 with 56k miles

 

was it a milky grey? if so thats water

 

I changed the rear diff. fluid in my car at 6K miles and it was a greenish grey color and smelled nasty.

 

Metal in the oil will turn it grey also

 

what if it was a yellowish color?

 

no just a gray? but one on my wheeling buddies said its cause it had got water in it and mixed with the oil.. im not sure what the trucks been trough i bought it used so im doing all my servicing to so i know that its been done

 

Water would cause it to turn grey. Anytime your axle is under water, the fluid should be changed right away. I think 75W140 is the standard now for all of our trucks! Its about $17 a qaurt so use it wisely

 

Royal Purple is only $9.99 at Pep Boys.

 

I did my front diff at 29,500 and it was a light grey/white with a thick white paste in the bottom. Told the dealer about it and he blamed the aluminum housing.

Can the aluminum housing cause enough condensation to turn the fluid white?
I drive short trips to work and live in MN where temps and humidity can very a lot the same day.

I'll be checking it often.