Sudden Increase in Oil Pressure

[ahramin]

After an oil change from W100 to W100 plus, the oil pressure on our O-375 jumped up. In cruise it's normally ~85 psi, now it's at 104. Both with an oil temperature of 190F. Assuming the oil pressure sender checks out ok, does anyone know of something that could cause oil pressure to suddenly increase 15 to 20 psi?

Thank you.

[cub builder]

Oil pressure regulator on the right side of the case above the dipstick tube. Take is apart, clean reassemble. If you have the adjustable one, adjust appropriately. If you don't you may need to replace the spring or remove some washers from under the spring if there are some in there. Assuming your oil pressure gauge is correct, that's likely to be your culprit.

[ahramin]

Thank you. Turned out to be a bad EFIS ground.