Getting ready to do my first oil change (always had it done at the local LR dealership which is no longer an option without a 90 mile drive) & was reading the oil & filter change post. I know the owner's manual calls for 5W/40 if the ambient temp is over 85 degrees, but the gallon jug shows shell (non-synthetic) 15W/40. Is it a misprint in the owners manual? If not, what are the benefits? Also, the dealership always suggested & used synthetic, so is there a benefit to the dyno-type oil?

 

The first number deals with cold weather starts. The second number deals with warm weather. 15W40 is fine for you in summer, in your winter below 15F you might want 5W40 Rotella (syn). The dino oil is not the issue, the diesel rated is what is good, because more cleaning compounds and extra ZDDP which is good for flat tappet style engines of the 60's.

 

Perfect, thanks!!

 

If its always had synthetic in it you might as well stick with it. It will only help to keep your engine clean.