improved mileage with changeout of gear oil?

[White Rim]

A 1000 miles ago I replaced the black OEM sludge in the R diff with Mobil 1 75w-90. Yesterday I finally got round to replacing the sludge in the F diff also. The black sludge must be straight weight 90, it was much more viscous than the 75w-90. It could be because it was so loaded with iron but I think it was actually opaque to begin with.

I also changed out the MT6 and XFR gear oils. The transfer oil was slightly worn looking but the MT6 oil looked amazingly good for 25000 miles.

I wonder why the diff oil in F and R were both so opaque and thick. "Could it be a graphite loaded gear oil?" I asked myself.

I was quite astonished at how black and opaque it was. Just like graphite grease.

Anyway, it may be my imaginiation, but the scangague seems to be runnign a little higher milage now. I wont know for sure till after a few tanks.

It certainly stands to reason that the synthetic lower viscosty could help a bit on the mileage.

The differential housings no longer have that nice orange glow they had with the sludge.

[AceTechno]

You should notice a small increase in mileage, But nothing to write home about. I am running full synth everywhere and all I noticed with my scanguage was like 1 mpg better. Well that worked out to about 15-18 more miles per tank. That for me resulted in one more round trip to and from work and one extra trip to Taco Bell. So I was happy "with a full belly".

[FullTimeStud]

I am running Mobil 1 Synthetic in everything, and I havent seen a noticeable change in mileage.

[ballkillerxxx]

well even 1 mpg is a good thing now days