wrong fluid in rear diff.....

[blue_goose]

So I changed the diff fluid in the rear and put in 85W-90 instead of 85W-140. I change it every year in december with the thought that the rear diff will last longer since it has been humming since I got it at 87k 5 years ago. (at 145k now). So can I leave this in til next year or will it really mess stuff up in there? its not like its dry or anything..... any ideas?

 

[dwcopple]

3.55 or 3.73?

 

[IZwack]

Itll probably be fine over the winter and as long as you dont tow.

 

[blue_goose]

3.55 its mostly highway that I do with little towing so I'm going to hope it will be ok. thanks for the help.

 

[Limited02]

I don't know my oils all that well, but the first number(85W) has to do with the viscosity of the oil is when it's cold and the second(140) is the viscosity when hot(at operating temp). That's why in the winter, some people go from a 5W-20 to a 0W-20 because it's easier to start the motor when it's really cold out. If someone can better explain this, please do.

So as you know, the rear end does A LOT of the work and will get hot especially since you tow everynow and then. I wouldn't worry to much right now since winter is coming, but if you do plan on towing or getting goosy with the gas, I'd see about changing it to the higher oil since it's easy and cheaper than a new rear end