Differential gear lube.
This may be like asking "which is the best brand of oil" but I need opinions. I'm due to change the differential gear lube in my 2005 Dodge 2500. Last time I used Mobil 1 synthetic 75W-90. I should...
Forum Discussion
dryfly wrote:fj12ryder wrote:
Dodge recommends 75-140 for heavy duty towing. Can't imagine why one would want a less viscous lube. It's not like it is being pumped, it just cushions and lubes.
Well, you would think so but I've read threads where guys are measuring the differential temps and report higher temps with the 75-140 vs. the 75-90. Very confusing. I'll bet 90% of the folks pulling trailers have no idea of the need for aluminum covers or going to heavier weigh lube, and you seldom hear of rear ends failing.
I've run Mobil 1 75W-90 with a stock diff cover now for 55K miles pulling 9000lbs. No evidence of over heating by looking at the paint on the cover.
I just talked with the Mobile 1 tech support. I told him my concern about the 140 running hotter and he said because of the increased friction from a heavier oil it's very possible. However, he also said it would be very little increase in temps and if you do in fact need a thicker viscosity you need to go that route. Problem is how do you determine that? If the 90 is not showing any visable signs of heat or is not causing rear end noises, who knows.
I asked him about mixing the 90 and the 140 weights together in a 50/50 ratio and he said that would be fine. That sounds like a good compromise to me. Similar to Amsoil 110w.
