I own a Jaguar Supercharged XJ 2011 and asked a company to perform an oil change with oil I provided them I bought at WalMart. I used 5 quarter of a 0w-20 full synthetic oil as recommended in the U.S. and an European grade Mobil 0w-40 full synthetic oil for 2.5 quarter (this type of oil is recommended for the car in Europe and is known to have better results for car engine longevity and reliability). The result is quite superb with a more responsive car, less shaky and noisy engine, and a better fuel economy than I am used to. By being extra careful, I was able to achieve driving around 40mph for 15 miles an average of 28.5 mpg. I did not want to wait another 6 months and have my car serviced at the Jaguar dealership as I drive an average of 6-7k miles per year. Please share your experience when an oil change was performed by your dealer or yourself.

 

I think you are right to recognise your lower mileage and change oil at less miles, but probably yearly. It is tootling around town that does the damage and causes oil to deteriorate.

Oil is cheap, engines are expensive !

 

Are you saying you deliberately mixed two different viscosities of oil? May I ask why?

 

Yea, I'm interested too as the reasoning behind mixing the two oil types...why not go with only the European recommendation of 0W-40?

 

Unless I'm more confused than usual, the owners manual states:

Petrol engines SAE 5W-20 meeting Jaguar
specification WSS
M2C925-A only


so neither oil used by the OP is correct (?)

 

There is no harm mixing full synthetic oils. The 0w-40 is much thicker than the 0w-20 probably due to its additional chemicals for additional protection and wear. The Mobil 0w-40 is the only oil approved for AMG and the Nissan GTR - and probably the best oil for extended protection in the American market. No change is required for 12-15k miles. Since, I expect to change the engine oil every 7-8k miles, I only use 2.5 qters out of the 7.5 qters. It is a known fact that car makers recommend typically 5w-20 to comply and achieve higher mpg. Doing so, they sacrifice durability and reliability. Mixing both oil helps to achieve the best of both world.

 

Oh boy. Good luck.