The age old questions about oil and oil filters never stops so here's some info on oil filters. I've used both of these filters on my car and this brand of filter on all my vehicles as well as our work fleet, have had good results so far. I took a NAPA 1334 filter with glass enhanced cellulose media and a NAPA 41334 filter with metal backed synthetic media, as you can tell by the numbers these filters are twins on the outside and as far as GPM specs but the inside tells a different story. Before we get to that though, lets do a quick run down on both of these. For the 1334 the average cost is 8 bucks, not bad at all because it definitely is a good quality filter (all NAPA filters are made by Wix) it has a 21 micron rating, 9-11 GPM and NO bypass. The 41334 runs about 13 bucks, not bad but I know people who think filters like the 31334 at 4 bucks is too much (they're clearly not as anal as us ) also 9-11 GPM and has a bypass valve set for 8-11 PSI, I couldn't find any micron ratings for it. So now we let the pictures do the talking, after all they're worth a thousand words a piece right? What I took out of doing this is I'm glad I now use the 41334, the media is thicker and has more of a surface area for garbage to get caught. I could live without the bypass valve but I'll let that go since synthetic is mostly used in higher performance vehicles and more likely to need it. Here's a link with some excellent information as well http://www.trailerlife.com/trailer-h...e-oil-filters/

PICTURES: http://s95.photobucket.com/user/DTyl...0Oil%20Filters

Sorry about the less than great photos, only have a 5MP phone camera. This should give you a general idea of what's inside and what you're looking for though.