After my pickup was leaking oil, I replaced all of the gaskets and seals that were leaking. My pickup now has a spotless engine. But after this, the oil kept reducing by 1 ½ quarts every 200 miles. I changed the PCV valve to see if that was the cause, but that did not make any difference. When I looked at the oil, it looks normal in color and consistency and so does the coolant. The exhaust is not smoking. Running a compression test, without oil, was 120-130 psi on all cylinders. It seems to me that burning 1 ½ quarts every 200 miles would be showing some smoke. I am using old oil because purchasing new oil on a constant basis was getting too expensive! I am wondering if perhaps it is running a little rich and that is why it’s burning oil so quickly. What is your advice for fixing this problem?
Hello there, thank you for asking about your 1994 Isuzu Pickup. For your vehicle, minimum compression is 114 PSI and all cylinders should read within 70% of each other. So, according to your results, compression is good. My guess is that the clearance between the valve guides and valves is excessive or that the valve guides seals are worn. Either scenario could result in an engine that sucks down oil but still has good compression. Either way, a quart and a half every 200 miles means something is wrong, very wrong. I suggest you have a professional, such as one from YourMechanic, diagnose your low oil problem and repair your truck firsthand.
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