2007.5-2009 Dodge 6.7L Cummins Differential Fluid

Gear oil for the 2007.5-2009 Ram 6.7L Cummins

Under your Cummins-powered Ram sit two American Axle differentials if it is a 4x4: a 9.25-inch front that holds 2.45 quarts and an 11.5-inch rear that holds 3.8 to 4.2 quarts. 2WD trucks only have the rear. The severe-service change interval is 15,000 miles or 12 months. Your owner's manual defines severe service and lists the front axle grade.

Choosing a grade

For the rear, the documented spec is 75W-90 full synthetic, with 75W-140 synthetic for heavy towing. Synthetic gear oil is one of the catalogued driveline upgrades for these trucks. You will also find 80W-90, 80W-110 and 85W-140 grades on this page. Those are not the rear spec we have on file, so check your owner's manual or call us before you put one in.

What we carry

Hot Shot's Secret is here in its Adrenaline synthetic racing gear oil and Blue Diamond HD synthetic gear oil lines, each in 75W-90, 80W-110 and 85W-140. Lucas Oil covers both camps with 10047 synthetic 75W-90 and 10121 synthetic 75W-140, plus 10043 heavy-duty 80W-90 and 10042 heavy-duty 85W-140. Royal Purple rounds it out with 01301 Max-Gear 75W-140 synthetic.

Fitment notes

These oils are not built for one truck; what makes them right for yours is the grade and the quantity. Buy enough for the rear capacity range, plus the front on a 4x4. SRW and DRW 3500s share the AAM 11.5 family, so the same rear spec applies, though hubs and track differ.

Frequently asked questions

How many quarts of gear oil does my rear axle need?

The AAM 11.5 rear on a 2007.5-2009 Ram 2500 or 3500 holds 3.8 to 4.2 quarts. Since the range runs past four quarts, have a fifth on hand. A 4x4 front 9.25 needs another 2.45 quarts.

When should I step up to 75W-140?

The documented spec for the rear AAM 11.5 is 75W-90 full synthetic, with 75W-140 synthetic for heavy towing. If your Ram spends much of its life hooked to a heavy trailer, step up. Lucas Oil 10121 and Royal Purple 01301 are the 75W-140 synthetics on this page.

How often should I change it?

The severe-service interval is 15,000 miles or 12 months. Your owner's manual defines what counts as severe service for your truck.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.