Had a purolator on from the last oil change. sometime while driving, not immediately after oil change, but somewhere in between, my oil pressure gauge dropped from its usual, (which was- over 50 while warming up, driving around 40 and then at idle somewhere around 20?) to only 20-40. I've read about it and it seems the gauge is notorious for being inaccurate and that as long as it never went to 0, I may be good. However, after the purolator it never seemed to get above 40, ever. I didn;t realize all of this until I changed my oil the other day. Got a mobil 1 filter this time. and now I am baclk to over 50 warm up, constant 40 while driving and 20+ at idle. Does this make any sense and is purolator something to avoid? I have eliminated my oil cooler, a while back. The oil filter that is recommended seems to me smaller than it should as I have AWD and it is tight up in there. any thoughts?