Which oil pump

When the oil gets hot it tends to thin down (lower oil pressure) and goes back to normal when it cools. I use the Mellings HV oil pump in my 440 and it idles @ 85 ish with Mobil 1 20-50W fully synthetic, have never seen it drop below 70 PSI though. Also I use the Fram HP-1 oil filter it has the anti drain back valve and filters down to 18 microns and has heavy duty construction. The Fram oil filter cost more and when used with the Mellings HV oil the 20-50W oil I use probably robs at least 10 HP but for me I like cheap insurance and have never had any kind of engine failure with it.