94 gt oil pressure

My 94 gt has the quad 4 dohc ho engine. The oil pressure seems low when it's running warm or hot. Around 17-19 psi. When driving i'm estimating 25-30 psi. Is this normal or is it too low? It has gone lower too, maybe the cold weather, or after I changed the spark plugs or even the oil additive i had put in. But i'm assuming because that additive had a higher viscosity than the engine oil it wouldn't make much of a difference. The oil I believe was a synthetic blend, i had a shop change the oil and the reciept said synthetic blend. Should i get the oil changed to regular oil or is there maybe another problem or is the pressure low? The oil pressure is around 60 psi on start up.

The only thing you might want to consider would be to change the sending unit on the oil pressure guage. Based on what you state I am assuming that this is a high mileage vehicle. As parts wear oil pressure naturally decreases. 30 PSI while running is a bit low but not out of the ordinary. If I were you I wouldn't change anything on the oil other than possibly going with full synthetic. It will lubricate better and the engine will last longer. Otherwise keep an eye on the pressure as long as it doesn't drop too low you should be OK!

The engine has about 114k miles on it. Yeah high mileage but not too bad i think. So the oil pressure sending unit could be bad you say? Where is that located and is it hard to replace?

It should be located above the oil filter. Looks like a round can with a wire coming out of it. It is not hard to change and shouldn't be too expensive.

It should be located above the oil filter. Looks like a round can with a wire coming out of it. It is not hard to change and shouldn't be too expensive.

Actually, isn't the oil sending unit located on the driver side of the engine just to the rear of the power steering pump. But I have a question for GTP, why go synthetic to increase pressure. Isn't synthetic thinner? Why not go to 10W- vs 5W- in order to increase the thickness. But then that would only increase pressure in the beginning I guess until they both got hot. And what about additives? Any luck there? ... Thanks, Bill

The reason I said to go with synthetic is because it lubricates better and will not break down like dino oil. This way the oil will keep the engine lubricated better despite the lower pressure. And contrary to popular belief the synthetic oil stays at the same viscosity as the non-synthetic. A heavier oil will boost the oil pressure slightly but like you stated unless he went with a 10w-40 or 20w-50 he won't see any significant increase when the engine is hot. Additives really won't do anything.

Thanks for the oil sending unit location. The Quad 4HO is a slight mystery since I really have never seen one up close and personal.

Okay I'm pretty sure the last oil change i had it was a synthetic blend. That's what it said on the reciept anyways. Should i ask or maybe make sure that a synthetic blend is put in the next time and then go to full synthetic or just go right to the synthetic? I have heard that switching right to a full synthetic can really damage an engine. Is that true?

No, switching to synthetic will not damage your engine. Sometimes with certain engines you may get a valve cover gasket leak due to synthetic but they are the only gaskets that are affected. Pontiac coated the gaskets with lacquer and the synthetic oil will dissolve it and cause the gasket to leak. Otherwise no damage will occur.

I'm a little concerned about that gasket leaking, i don't want to have to keep filling the car with oil. Is this definate thing or is it possible? And is there a newer gasket that will be able to handle the synthetic oil?

A newer neoprene gasket will handle it with no problems. The old cork gaskets were the ones that would leak. You should be able to find one at a local auto supply store for a few dollars.

I changed to full synthetic in my quad and didn't have any oil leaks. When I tore it down to change the head I noticed that the valve gaskets are not cork, they are a fiber type.

I'm not really sure where the gasket is. Would it be hard for a novice like me to replace, just to be on the safe side? Would our quads have the same gasket with mine being the dohc h.o. version? Or would going full synthetic be just fine to try anyways?

Because you have the HO it is possible that you already have neoprene gaskets. I would go to the synthetic oil and not worry about a leak. If it happens any novice with some basic hand tools can change it in about an hour.

arent some of these newr gaskets silicone? or neoprene . They hold up to extreme heat well.

The top gasket is very easy to change on both cams, but changing the lower gasket means removing the timing chain, which is an involved job.

Okay well I will go synthetic then. The car has somewhat low mileage for it's year (114,000 about) and i'll only have put about 5,000 on in one year so switching now would probably be good. And thank you for all the help. :)