I had my $9.00 harbor freight gauges calibrated. I was blown away, they are within 1/2psig accuracy!!!! I also had the smith gauge calibrated, it is off 3 psig at 60 psig, so when the gauge reads 60 actual is 63 psig. What this is telling us is I have a 7 psig pressure drop across my
oil cooler and associated plumbing!!!!!!!!!!!!!!!!!! Melling sets up their
oil pumps to relieve at 60psig, if you installed without increasing the factory setting the most
oil pressure you would see on your dash with an oil cooler set up is 53 psig!!!!!!!!!!!!!!!!!!!.
In summary pressure drop across the FL-1HP is neglibible to the point you are guaranteed 100 filtration at any ambient temp above 50F.
If you run an oil cooler you need to jack up the rv setting on the oil pump to account for the pressure drop or you will not get the desired 10 psig per 1000 rpm's.
When my oil was cold I was getting reading of 75 psig at the filter and 67 psig at the gauge on the dash. So my oil pump rv is set at 75 psig.
For 99% oil coolers are a waste, it takes longer for the oil to warm, it requires higher discharge pressure from the oil pump. The only good thing is differential pressure testing across the oil filters. From now on I am sticking with the Motorcraft FL-1A from walmart at $3.85 instead of the $15.00 FL-1hp.