'96 XJ 4.0 here and I was wondering what's up with this Mobile 1 oil I've just found. Website says it's good for a full year or 20k miles, whichever comes first. I've been using Mobil 1 high mileage/extended life and change out every 5k miles with a Wix filter. Should I switch over to this stuff and just change out every year (which is 10 k for me)?

Btw, apparently it's only offered in 0W-20, 5W-20 and 5W-30.

I'm old school WRT oil changes.

If you want to use any synthetic, start when the engine is new (or rebuilt). Switching from regular to synthetic is a good path to leaks....

Change the oil periodically. If you drive short or stop and go trips, change it more frequent, about 3000 miles.

If you do long periods of highway speed, you can stretch out to 5000-6000 miles.

Oil will build up acidic residue that needs the heats to keep in check.

I don't have any experience with the Mobile 1 Annual Protection. It does go against my feelings about oil change frequencies. I keep fresh oil in my vehicles....