Good thought but my book says 8 years/80k. I'm over on both.

I've replaced the gas cap already. Any suggestions as to check next. Also, where is the carbon canister located on a 2008? I was going to check the hoses going into it for leaks.

The only replacement part available is the entire filter housing. Since my original posting a Volvo tech has told me that it is a drain hole plug for draining the dirty oil when the filter is removed. I'm just going to find a used housing and swap out the part.

So, I was doing a typical oil change that I've done numerous times before and I found loose rubber disc about 1/2 inch in diameter in the bottom of the oil filter housing. It looks like it was attached to a piece of spring steel that gets pushed down to close a small hole at the bottom of the filter...