Mobil 80W140

[BLee]

Last night my son-in-law and I installed the Mag-Hytec Diff Cover. Per suggestions here, we used Mobil 80W140 full synth gear oil. My truck has LSD, so I had bought the friction modifier from my Dodge dealer. I previously noticed on the bottles of Mobil! 75W90 in an auto parts store that 75W90 already contains friction modifiers. Suspecting that the heavier oil did also, I didn't add the modifier last night. I've driven it about 35 miles so far, with no chattering at all. Is this everyone else's experience with Mobil 80W140 synth, or should I go ahead and add some friction modifier? Only problem with this gear oil is it comes in 5 gal pails. Good news is the son-in-law's '97 2500CTD 4X4 is ready for a change also. The Mag-Hytec appears to be really well engineered and thought out. Fit perfect, no leaks, looks great.

 

[John Berger]

Don't know much about that lube. I use Amsoil 75W-140. Make sure you do 8-10 figure eights to get that LSD properly lubed.