On the early 3.4 engine I am using the stock oil filter setup is inverted. Later one on my junk engine facing down. I'd like to replace the factory type with a spin on. Should I replace the inverted setup with the later one and then buy the spin on? It seems there is a different part number for both types spin on.

 

I prefer downward pointing. If I'm careful, I'm less likely to spill a load of oil when changing the filter plus the filter is definitely already full of oil at cold starts.

 

I agree with Peter ~ downward facing. As long as you change the spin on cartridge every time you change the oil.

The original housing with a modern element has greater debris carrying capacity by some margin & you could change the filter every second oil change if you adhere to Jaguar's short drain intervals.

The trick being ~ is that used filters do a better & better job as they blind AS LONG AS YOU DON'T LET THEM GO INTO BYPASS.

Regular oil analysis will guide you. Jaguar's drain intervals are ridiculously short if you use modern lubricants.

 

Spin-on is easier. Less messy. I got mine from Home of Classic Jaguar and Team CJ

 

And smaller media area. Made for convenience.