Your R1100S uses the same 845 oil filter as many other Oilheads, including my R1100RT.
I have used the Bosch 3330 filter, also the Bosch 72161 filter, they both will work and use the same filter wrench as the 845 filter. If you search around for the Mahle OC91 oil filter, you will have the OEM oil filter for about 1/2 the price. If you can order the OC91D, you'll get the crush washers in the box too.
Two famous brands, "HiFlo" and "K&N" make filters for our bikes - all the boxers - and the distinguishing aspect of each can is the 17mm nut welded on the end.
So there's no need to p*ss about with the special BMW / Mahle wrench to get the thing in and out.
All you have to worry about is making sure the old rubber ring isn't still stuck up inside the cavity after removing the used filter....
...and the other thing is not to over-tighten the new one after you've run your oily finger round its mating surface. Just snick it up by hand and then give one eighth of a turn on the spanner. The new rubber / neoprene sealing ring makes an oil-tight closure at all temperatures. No need at all to wring its goolies off. AL in s.e. Spain
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