[Juma]

All models for the Ram 1500 specify 75w140 rear end lubricant. I almost never tow or carry a more than 500 pounds. I have the V-6 and drive it very easy. Could I use a lighter weight differential lube like 75w110?

 

[Blackhawk]

Why would you want to? Fuel economy? You will never see it. I would stick with the factory recommendation. Have any differential problems - by, by warranty if they find you are using the wrong fluid.