My jag xf oil level is 3/4 full ...should I top this up now ?

 

No.

If you are relying on the dipstick then 3/4 is ample. If yours has the electronic oil level display it tells you when you need to add oil.

A sump full to the "max" mark is no longer important because oil consumption is very low.

At 3/4 you still have more than 6 litres of oil in a 4.2 and even more in a 5.0 or 3.0 SCV6.

 

If there are no leaks, you don't use maximum performance to go everywhere or do a lot of short runs, the level shouldn't drop from Max down to Min between scheduled oil changes.

Graham