That old oil filter thrust washer can of worms.

[Cheburashka]

OK, I get the feeling that diving into the "which side of the oil filter does the thrust washer go on" debate would probably stir up a hornet's nest, but after looking at the way it's set up and accepting the wisdom of having the thrust washer on the outside, I'm left with one simple question.

Why not a thrust washer on each side?

I can see the purpose of having it on the ouside, inboard of the pin. That prevents aluminum on aluminum contact on that outside bearing. But isn't the inboard side of the pin also inserted into aluminum? Isn't there aluminum on aluminum contact on that side?

I ask because when I pulled my oil filter for the first time, the thrust washer was inboard of the filter. Also, the filter shaft was in pretty bad shape, so I ended up buying a new filter and shaft. I figure if the steel shaft got worn down, there's not much chance that the original filter's aluminum bearing surface survived intact. Now that I'm putting in a new filter, I want to make sure I don't end up with the same problem again.