I use supertech oil filters because of the quality vs price ratio. I know black OEM is the best but I dont want to spend more than double what I pay for the ST filters.

 

I see some people online say ST6607 whereas ST3593a is what comes up when I do a application search. I have been using the st3593a for years. The ST6607 looks a little higher quality but is smaller. I cant find specs on either to compare. Anyone know if the bypass spec is the same on these? Any reason to use one over the other?

Here's some info regarding the smaller vs. larger oil filters.

 

http://ultimatesubaru.org/forum/showthread.php?t=126302

I don't think anyone on this forum is going to know the answer regarding oil filter bypass specs. Prolly only the manufacturer knows that. I use, and have used for years the Walmart brand supertech filters. I have always used the 3593 size in my Subie with no problems. I see no reason to switch to another size.

I know that purolator is the only filter with a high bypass number 20-25 lbs. But they have no anti drainback valve. Six has the valve bit low bypass numbers 8. I went with stock.

Wix

For most Subaru motors the anti-drain back valve is not necessary since the filter sits vertically with the base or "bowl" downward.

Wow. That's a damn good point josh. Oil can't drain up! Might go with purolator filters . Pure one is a quality filter that has stock bypass pressure.