It's not terribly hard to see if the 20-500 will fit or not, since it is thinner you only need to look at the bottom of the filter area, is there an inch extra from where you back the filter up? Or is their an obstruction that exists. You have to consider the depth with the current filter backed off position sitting on the threads, there is either an inch extra or there isnt. I wouldnt even bother to mention it as like I said the fram xg2 is a great option, but RP filter media was proven over fram ultra in my wife's car.
She has a cartridge filter otherwise we probably wouldnt know this information. I stored the filters in her truck, the fram ultra went stiff overtime with heat cycles in her trunk and the RP didnt, the rp cartridge media was like new even though it was in her trunk longer. The information we currently don't have is fram ultra xg2 cut open after a long interval, or at least a couple of them. It would be helpful if we did. The media that went stiff in the trunk was the pink/yellow fram ultra filter, the rumor is they upgraded. We either need someone who visits the walmart shelf to open the ultra box on a cartridge filter and note the color, it was be real helpful if someone bought an xg2 off the shelf and cut it open, if it is white you should be good to go, if not well there ya go. I almost did this, but personally I spent a lot of effort finding my filter and I'm very comfortable where I am at, but someone might consider doing this.
Look at the color of
this media.