I don't want to "flame" you, but you DO want responses or you would not post at all.

Ok, so...

Why not go to your local oil change shop and tell them to use whatever oil and filters that will result in a $35 oil change?

What I mean is - how far are you going to carry this struggle to save money on that car? Where do you draw the line now that you are throwing out the manufacturer's recommendation on fuel?

MY PERSPECTIVE: I was told before I bought this car that maintaining it was going to cost more than I was accustomed to. I thought long about it, and when I was done thinking, I was prepared for $120 oil changes and sets of tires that cost $1,000.

REALITY: Gas costs 35 cents per gallon more for the XF than my truck. *yawn* Big Deal.