TOPIC:

Has the oil filter washer (above the spring) on the A4 model been omitted. The reason I ask is the bike is unmolested but when I removed the oil filter there was no washer installed. The spring is machined flat on both ends but the ones I've seen on eBay are round. Possible the previous owner has misplaced it but I can't find anything in the manual to say it has been omitted on later models.

If the washer you refer to is similar to my '80 then I would suggest it's a "buffer" between the spring and the rubber on the filter. I'd find one that fit and use it.

Are you sure it's missing? When doing an oil change, I find the washer is always stuck to the bottom of the filter. When I go to put the new filter on, I can't find the washer, then remember to check the bottom of the old filter.