I’ve been burning about a quart of oil every 400 miles so decided to do a leak down and compression test.

The compression test went well with 135, 140, 145 and 150. The battery seemed to be getting weaker so the lower readings may be higher. They connectivity reduced from 150 to 135.

Leak down didn’t go so well. I bought a Harbor Freight tester and it seemed to only test with about 25 psi even though I was putting 100psi into it. The first cylinder showed 10% leak.

My question is, Is 10% at 25 psi the same as 10% at 100psi? Shouldn’t I be testing at a higher psi?

I am returning the tester since I can’t hardly adjust it precise enough. What is a good tester to use and does anyone rent them? Autozone does nit.