The oil in my Viper is usually changed based on time (three months) before I ever see the miles change number.... i.e. the oil is still clean. I've used the NAPA Gold filter and been pretty happy with it. But since my oil never seems to be dirty, it must work well... LOL
How did I end up at the NAPA Gold filter?
Well, a fellow used to have REALLY NEAT site on just oil filters, we love Vipers, well this guy loved oil filters (It takes all kinds

). Anyway, for fun, he buy's oil filters, cuts them open and reverse engineers them. He measures can volumes, length of the filter media, the filter medias "pore size", type of construction, if they had check valves, types of check valves,
"Neat ideas", and just an infinite number of stuff that only engineering nerds love. Well, the NAPA Gold/WIX filter seems to me to be a good value as often as I change filters (every thre months).
Check it out:
http://minimopar.knizefamily.net/oilfilterstudy.html
Here is what he says about the Mobil 1 Filter (note comments on splits, the fellow from Team Viper mentioned this during the N. TX Tech Seminar, but he thought it had been taken care of):
Mobil 1
M1-301
Like the Champ filter, this filter is made by Champion Labs. However, it uses a unique end plate and a thicker can that make it the strongest filter available for wide distribution retail sale. It also uses a synthetic media, which inproves filtration and flow. I'm happy to say that this filter is not a fake. It is definitely a unique design.
It uses a synthetic fiber element that can filter out very small particles and is very strong. It is rated just under the Purolator Pure One as far as filtering capability, but is still very much above conventional paper filters. It also has a very strong construction to withstand high pressure spikes during start-up. However, as with all Mobil 1 products, expect to pay 2 - 3 times as much for this filter.
I have received many reports of these filters failing at high pressures. It seems that the seam where the backplate crimps to the case can split.
Average Retail Price $10
Cartridge Length 4.250 inches
Cartridge Outside Diameter 3.250 inches
Cartridge Inside Diameter 1.625 inches
Cartridge Pleats 52
Cartridge End Cap Type Stamped-steel, with bypass valve
Anti-Drainback Valve Type Nitrile rubber diaphragm
Bypass Valve Type Spring-loaded steel, nitrile seal
Element Type Synthetic media, glued seam
Element Length 85 inches
Element Width 4.125 inches
Element Surface Area 351 square inches
Shell Thickness 0.022 inches
Backplate Thickness 0.138 inches
Gasket Type Nitrile rubber