I have an '03 4.2 S-type, purchased new. Currently have 59,000 miles. Jag dealer has always recommended using 5w 30, but not synthetic. Anyone have thoughts on the issue? Thinking about going to synthetic.

Thanks!

 

The issue has been beaten to death a multitude of times with no conclusions reached. Lots of epic battles in the archives if you want to search. There is no requirement by Jag to use synthetic on this car nor can anyone demonstrate any real-world advantages that affect the life or operation of the engine.

Use what ever type of oil you like that meets the viscosity and API requirements as listed in the owner's manual. You'll be happiest even though your car couldn't care less.

 

I have 2003 STR, I have always used synthetic. I remember dealer saying the same thing, but I use anyway no ill effects. Dino and synthetic either way is OK.