Considering that the oil filter is top mounted and it is a cartridge type filter is there a check valve built into the filter. I am used to the Ferrari and Audi top mount filters but they are both spin on types with a one way valve in them. You can remove them without much oil coming out . So I guess my question is does the Jag filter drain back into the block (this means the filter is empty on start) or is there a method of retaining the oil built into the filter housing. Also at oil change do you vacuum out the oil before you remove the filter.

 

The first step of the workshop manual procedure for changing the filter element is to unscrew the filter housing 4 turns and then allow the engine oil to drain from the housing for two minutes. So, presumably, if you don't unscrew it, the oil stays in the filter.

And the oil change procedure requires you to follow the same process before extracting (or draining) the oil.