I am thinking of using 75-140 oil. Will it hurt my mileage? Thanks All.

 

It did not hurt my mileage at all. I got the same milage after. Also, Dodge has changed their recommendation to using the 75w140 in the diffs. Some are using the new 75w110 from Amsoil. I tow, drive on hot roads, so it was a no brainer. There is a discussion over at http://www.carsondodge.com/Forums/index.php regarding which oil to use in the diffs. You can also joint the forum and ask questions specifically.

CD

 

When I changed mine I went to 75w-140 from royal purple and it seemed like a thinner oil.Poured much easier than what I took out ,i'm gonna do the front diff but use 75w-90 by RP.
Joe

 

Amsoil also makes a 75w-110 that is not suppose to hurt mileage like 75w-140 does.

 

Put RP 75W-90 in front and rear and been very happy.

 

I went from 75wX90 in the rear to Royal Purple 85wX140 and noticed no difference in mileage. I have RP 75wX90 in the front.

 

Ditto - that was on my 97 in Co. winters. I'm going to RP 85w140 in the 03 next. Craig