TomRosenstock

I’ve been having some oil pressure issues. I'm back in the US after 5 years in Afghanistan, taking my wife and baby on a vacation road trip, towing a trailer, so unfortunately I don't have lots of time to stop and let shops play with it, I'm also not at home or near a knowledgeable mechanic I know (and I myself know next to nothing about engines).

Three weeks ago I bought a 2001 Chevy Tahoe with 154K miles on it, got a great thumbs up when I took it in for a prep-purchase inspection. Lifters were making a little noise, so I added Lucas oil additive and had the oil changed. That quieted everything down. Ran great for a while, but now the oil pressure seems funny. For the first 1500 miles or so it sat around 40PSI. Then it dropped to around 20, and I figured I should get a change soon, so I picked up another quart of Lucas.

This morning at around 2200 miles since the last oil change, it started dropping to 15, and I heard a faint clicking, then 10, then 5/0, then I started to lose power. I was on the side of the highway, so it was fortunate that I had bought the Lucas oil additive, I put that in and it seemed to be a little better, stopped at a gas station and put a quart of 5w30 in, and it got even better.

Then I got an oil change (and re-added the lucas). After the change I hoped it would go back to 40, but only went back to 25, then I drove about 50 miles (2 hours with some traffic) and it dropped to 20. I checked the oil level and it's full, so I don't think I'm losing/burning oil, the guys that did the oil change also said everything looked great.

I checked the online forums, and some people say the sensor can easily be messed up, but having felt the power loss, I'm worried it might be something more. It's not a brand new car, so I'm mentally ready for everything not being perfect. One suggestion online was to get 10W40, rather than the 5W30 that is recommended.

Any ideas or thoughts?

Much appreciated,.

Thanks,

Tom

SWHouston

Rather confusing...
The 10/40 is a pretty good idea, and when you change this time, don't put any more "additives" in it for now.
And with that, I'd get a Mechanical (analog) Gauge on it, and see what the pressure is actually doing.

corvetteguru

here is a sad truth... when a GM oil pressure sensor fails, it pegs at 80 PSI.

remove the oil fill cap and check the flow. You should see a slow moving river of oil at the lower edge of the head through the oil fill.

If not... you have an oil pressure problem... and that's either pump related or ... well... I would rather not address that until you have checked with a mechanical gauge.

FortBurb

Stay away from the lucas oil additive. It's a better idea to just run a slightly heavier oil.