I always keep junkWe had a leak in our oil cooler. It could have also been a leak on an oil pipe that goes from the cooler (area) to the side of the block (area) it was a common fault apparently, but no we had to have the expensive fix.
So save them O rings incase. Cos maybe related to @Mark Piercy comment.
J
This is the ones.. though i got 2, not 4
https://www.jgs4x4.co.uk/range-rover-l322-4-4-tdv8-oil-filter-includes-o-rings/