I changed my rear differential fluid yesterday with Valvoline Extreme Synthetic 75W90. I did not notice that one bottle was 75W140. This naturally was the first bottle that I put in and did not notice until it was to late.
With 3 quarts of 75W90 and one quart of 75W140 hurt anything or will they combine?

[quote=With 3 quarts of 75W90 and one quart of 75W140 hurt anything or will they combine?[/quote]


Hmmm, I think you just made 75W102.5. A new fluid that is not able to tow as heavy as 75W140 in the summmer nor able to flow as well as 75W90 in the winter!

Shouldn't hurt anything...

jb

Thanks Cougar, I figured it would be fine but was unsure of the thicker oil having a heavier density and not "slinging" right when the diff. gets hot.

I think the heavier oil is actually preferred when towing heavy loads in warmer weater.

Plus there both a 75 weight in the winter so your good there.

So I would say your good to go.

DD

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