Was just at Wallyworld and looked at their oil and saw Shell has a new Rotella "T5" 10W30 CJ4 Synthetic oil for $16/gallon. They also had the 5W40 "T6" CJ4 Synthetic oil for $19.50/gallon which is what I have been using. Can anyone chime in on the difference and when you should use which one? I'm not an oil expert but have been using the 5W40 Synthetic and changing myself at every 5000 miles.

 

5/40 is the primary oil to use according to the manual. Especially for towing.

I think if you look at the diesel supplement it also states you could go with the other oil during the winter based upon colder temps.

 

The T5 10W30 is a synthetic blend oil that's only suitable in our engines between 50 and 0 degrees. It can only be used for light driving and can NOT be used for towing.

 

I wonder why the Walmarts in S. Ca. are selling it. We definitely don't meet the temp. requirements. 5W40 or 15W40 is all we need. The only other difference is that the T-5 is a blend.