I used Baldwin oil filters based on the MultiFuel Filter and Gasket Interchangeability Chart (in the technical Article section) claim that they were the best fit. None of the gaskets that came with the Baldwin filter are the correct size. The chart recommends either a Baldwin B-241 or G-107 base gasket, I bought both and couldn't see any difference between them, both fit fine. I bought the filters on line from B-Line Filter & Supply (
http://www.blinefilter.com/) for $5.47 each, the gaskets were under a buck each. When I changed my filters I reused the fiber washers under the bolt head. One of them decided to leak so I went to my local parts store looking for a replacement. One place carried the Dorman line of misc parts, he had some fiber washers with the correct 1" ID bit the OD was slightly smaller. It worked just fine and they were pretty cheap, $0.50-$0.75 each so I bought a few extras.
How much are you guys paying for your WIX filters, and are both the base gasket and the fiber washer the right size?