When pulling a trailer (with the overdrive off) i lost 3 qt of oil in about 300 miles. I already replaced the O2 sensor, plugs, wires and the stock plenum with a Hughes kit thinking that was the problem but it persists. I dont get black smoke ever and the plugs all looked good. I think my rear seal is going out but if i was leaking that much wouldnt the bottom of the truck be covered in oil? Truck is a 1994 light 2500 with a 5.9 and 190000 miles with a hollowed out cat. Thanks for any suggestions

 

Check for leaks first. Especially around the valve covers, and the back side of the intake. Oil pressure sensor has been known to be a culprit as well.

Does your truck leave drip marks when parked?

If none of that finds the issue, time to do a compression test.

 

I was going to mention the oil pressure sensor as well. Good luck!

 

What about bad valve stem seals ?.

 

That *should* give you a puff of blue at start-up, but, may not be enough to actually see clouds while driving.

 

Hi Hey You sorry if I'm jacking this tread..just wondering if hey does a comp test what would show? Aside low comp in any or all cylinders..Thanks

 

low compression means weak rings which means more oil will come through and get burned in the cylinder. therefore, oil loss

 

Kool thanks for that! Would that clog the cat?

 

Why yes, yes it would. Fouls plugs, and trashes O2 sensors as well.