The Mobil 1 M1-110 just fits on the 1800. Clearances are tight but it doesn't jam if you line up to the threads first. Just strictly a personal preference but I like the longer filters in the hopes that more filter media means more trapped garbage and a cleaner engine with less pressure loss. But I don't have anything like facts and figures to back that opinion up.
That's why I'm doing a pressure drop test on these filters.
While it's obvious a longer filter has the ability to trap more debris over its lifetime, it is unclear if the longer filters offer more or less drop, simply because of their length or the type of filtering media they use. Some have stated just the opposite because on the premium filters like Pure One and Mobil One, they do use a different filtering media which filter out small micron size particles but cause higher pressure loss through the filter. If a filter is more restrictive, this lowers engine lube pressure to the engine. That's a bad thing.
There has been so much misinformation about using aftermarket filters on this site and others I participate in, I decided to perform an accurate test on many different brand filters to determine what the actual pressure drop is across them. I'll use my Goldwing as the test mule because it's so easy to perform the test on it but the net results would be the same on a VTX or any other engine. We're testing the pressure drop difference of each filter using a common testing device (the Goldwing) while performing a standard reference oil pressure test procedure as per the Honda manual.
Some have claimed some aftermarket filters produced as much as 20 psi less than OEM. That is significant and can cause long term engine damage which would not be apparent in the near term if using them. As modern design engines use the head material as the bearing surfaces for camshafts, it's critical to maintain oil pressure at these clearances or damage will result. Once these clearances are damaged, you have to replace the entire head because they don't use replaceable bearings. Hence the need to maintain OEM spec oil pressure. Personally I would not want to see a reading of more than 5 psi below an OEM filter reading.
I'll do the test when I get back from Daytona.
As of 3-7-12 looks like WalMart has officially deleted the SuperTec filters that fit the VTX from thier stock. These were made by Champion.
