The only brand of engine oil that I can find which meets the "Ford WSS-M2C925A" standard is the Castrol Edge Professional OE. Has anyone tried using Mobile 1 or other more reasonably priced brands? I'm not under warranty, so I am not concerned about losing coverage. I just don't want to damage my engine. Any information and advice is appreciated.

 

I have used Australian made oils, Penrite and Nulon, both reasonably priced, on both my XFR and F-Type with zero problems. Both are full synthetic 5W20, the Penrite bottle says it meets 925A and 945A, the Nulon bottle says it meets 945A but doesn't mention 925A.
Although the recommended oil for my F-Type is 0W20 I prefer to use 5W20 as I am in a fairly hot climate and the motor is essentially the same as what was in my XFR. As you are in Phoenix your climate would be very similar to mine.

 

I am glad to hear that no harm was done to either of your engines. :-) Do you have any input as to why the manufacturer states that the oil must meet the Ford 925A spec? Is this just a marketing ploy? In the US, the only oil that I can find which meets the 925A spec is the Castrol Professional OE, which - of course - only the dealer sells.

 

Because they made a test for oil so that people would think they needed to get that specific oil for the car. In reality no other oil company wants to pay to do a test that only applies to 1 specific application. Marketing at its finest.

 

I have used Walmart Supertech 05w/20 in my XFR for the last 3 years with NO issues, but I change it every 3kmi. and the fllter every 6kmi It's cost of $19 for five qts. allows me to do this fairly cheaply, and the oil filters (rated to last up to 15kmi) can be had cheap online.
The Jag engine is just like any other internal combustion engine, it's not made of unobtainium. Oil change frequency is the first priority in engine longevity. I use the same oil 10w30 with 5000mi change intervals in my 1998 Chevy Silverado with 289000mi.

 

", it's not made of unobtainium." - that's only because supplies of Unobtanium ran out in Castle Bromwich around the same time as walnut trees to make the dash became rarer...

 

The rare earth element "unobtainium" (Uo) is only used in the production of "plastic" auto parts. It has a half-life of 10 years. When enough of it decays, the plastic loses cohesion. Heat or ultraviolet light will react with "unobtainium" particularly in the presence of volatile molecules such as Ozone to accelerate decay. Many references to this element under the Jaguar Models (Classics) subforum.

Chemistry was my favorite subject in school.