I have a 91 s10 blazer sport, in order to get a reading from the oil i have to have the car running, with it off, it reads no oil, what causes this?

are talking about the oil pressure gauge? well, for one, there is no oil pressure when the engine is off. No kidding, there really isn’t. I wouldn’t fool ya.

Do you mean there’s no reading on the dipstick when the engine is off? If so, you’re dangerously low on oil and you’ve probably caused damage to your engine already.

If you pull the dipstick in the morning before running it, you get nothing on the dipstick? Has this always been the case?

Assuming you’re slluding to the dipstick…

You should check that with the engine off. Wipe the stick, stick it back in fully, remove and read. If there’s no oil there, you need to add to the “full” line.

Oil level may rise when the engine is running just due to agitation of the fluid splashing oil up the tube. This would not be abnormal.

i just bought the vehicle about a week ago, it has bad valve cover gaskets, would that have anything to do with it? if i drive it for 20 minutes or so, i turn it off, check it, and there is no reading, i turn it back on, then its full.

The oil is taking its time draining down into the pan. Why not just check it cold before you start it up?

This could be a sign that the oil isn’t draining down into the pan fast enough while you’re driving. Make sure you don’t have sludging or blocked oil passages. Your oil pressure stays high while you’re driving, right?

i will try checking it when it is cold and see what kind of reading i get. the oil pressure stays right around 40 psi while driving

If you’re talking about “a reading” on the dipstick, and you aren’t seeing an oil level when the engine is cold, the problem is that you are very low on oil.

What causes that is that you don’t have enough oil in your engine.

You will not get an accurate reading if you check the oil level with the engine running.

ok, i figured all this out, there is a breather type nut where the oil filter attatches that wasnt all the way tightened and it must have been loosing all the pressure when the vehicle was off. thanks to all of your guys help

I’m left a bit concerned about whether you’ve truely solved the problem. There is no breather type nut where the oil filter ataches, and there exists no oil pressure on any engine unless the engine is running.

Have you checked the oil level using the dipstick?

That same issue also concerns me.

This is the third potentially serious issue that the OP has posted regarding this vehicle that he/she recently bought.

He/she has told us in two other threads that:
There is a grinding noise coming from the front end, and that the left front tire is “leaning” when the steering wheel is turned.
We have also been told that the reverse gear on the automatic transmission is “getting weaker by the day”.

On a vehicle that is ~20 years old, the presence of a significant transmission problem is enough to “total” that vehicle. If you then add potentially dangerous front end problems and a situation of possible engine damage as a result of inadequate oil, it really sounds like this vehicle is ready for the great automotive graveyard in the sky.

I think that the OP needs to get all of these three potentially serious issues diagnosed by a mechanic a.s.a.p. in order to determine whether it is worthwhile to even consider repairing this vehicle.

I believe that continuing to throw money into this vehicle is probably a serious mistake, and that the OP needs some reality in the form of an estimate for repair of ALL of the issues. From afar, I think that repairing all of this vehicle’s problems would far exceed its book value, but only someone who can actually examine the vehicle can tell for sure.

Nice catch on the two other threads.

I’m also at this point concerned that the OP lacks the basic automotive knowledge to be looking into these issues him/herself. I too think it’d be a really good idea to pay a shop for an hours time to have the vehicle evaluated overall before spending any money.

I also think this is imperative because I too suspect there may be serious safety issues with this vehicle that make it unsafe on the road.

OP, your life and the lives of those you love may be at risk here. I urge you to make an appointment with a reputable shop.

I have a feeling that the guy who sold you the car put very heavy oil (or STP) in the crankcase to hide a well worn engine.

When you check the oil after shutting the engine off when cold, all the oil is still up in the engine and will take same time to drain down. Try an oil change (engine well warmed up) and put in regulal 5W30. If the truck starts consuming oil or smoking, my suspicion is correct.

As others have said, this vehicle will put you in the poorhouse if you try to correct all the problems you are reporting here and on other posts.

…and, the next time that the OP buys a used car, he/she really needs to have it vetted by a trusted mechanic prior to purchase.

The same money that will now be spent to diagnose the myriad problems with this vehicle would have been better-spent before buying it, thus preventing a waste of the few hundred bucks that he/she probably paid for this rolling wreck.

Unfortunately, this is a very painful way for the OP to learn this lesson, but the reality is that sellers of used cars will frequently lie about the condition and the maintenance of the vehicle, and may even go to lengths (such as heavy oil, as noted by Docnick) to conceal big problems.