Hello all!

Just to start out, I did do a search previous to creating this thread but did not really find an answer to my question.

I own a 1992 Camaro RS Heritage, 305 5.0L SBC, bone stock.

Car is my daily driver, I love her.

I have been using Royal Purple 10W-30 since...about a 6 months after I got her in march 2012, so lets say about two-three years. I heard RP is top of the line stuff so I said why not spend the extra money and make the car last longer.

I've noticed the oil pressure getting pretty low, ususally been staying just about the red line at idle and did some research basically to find that royal purple, and basically all other synthetics have very small particles compared to conventional oils, which is why the pressure is so low. I also changed the oil pressure switch with a new ACDelco and also a Standard one just to make sure it was reading correctly, so that is not the reason.

I have been searching for something else to put in my car that would bring the pressure back up..im sure if i start using conventional again, that would do the trick..im just not sure if there is a top of the line conventional that I would want to use?

I talked to a guy at pep boys speed shop, he recommended Rotella T 10W-30 triple protection heavy duty diesel oil..said it is really the same as conventional but has the additives that I want, like royal purple has, and it is thinker so it will bring my pressure up. He went on to say how additives that are left out of other conventional oils because they are bad for the environment, but diesels need them so they are in diesel oils, and shell Rotella is one of the best.

My questions -

Should I continue to use RP since SBCs really only need a PSI of 10 in order to operate correctly?
Is the guy at pep boys correct in his advice?
What is really the difference between diesel and regular car oil?
is this all a terrible idea and just use the cheapest conventional? (cause I have seen this advice on the forums many times.

Thank you!

 

How many miles on the car? Not uncommon to see pressure drop due to wear from miles

At idle you dont need alot of pressure. As long as oil has decent pressure at cruise rpm and wot i wouldnt worry.

But then again if the car spend majority of its life on other oils, then royal purple isnt going to save anything. Lol so cheaper is nice savings here

My 305 was low on pressure as well so i just went to a 10w-40 conventional and it improved pressure.

That all said i have run mobil 1 15w-40 diesel oil in my turbo car. I figured diesels are turbos and used alot in hauling so should be under harsher environments and see hotter temps. Ran it for a few years like that and everything seemed fine. Last tear down i did everything looked nice but that was a mix of mobil 1 10w-30 motor oil and then later on the diesel stuff. The thicker diesel stuff did do alot better in heat management. Oil pressure stayed higher

 

Car had 86,000 when i bought it, and now it has about 117,000.

used to idle at 30, then go to about 45ish when i gave it gas.

now it idles just above the red line and goes to 30 when i give it gas. when i floor it, it doesnt really go much higher than 30..maybe about a 16th of an inch higher? but not much.

no idea what the guy who owned it before me used.

All conventionals are really basically the same by law, just different additives based on the company, right? so there's no top of the line conventional, if that makes sense?

 

Here are some photos of the oil pressure levels. Lower one is at idle, higher one is at cruising speed.

 

IMHO you are in good shape . the sensors/gauges on our cars are known to be rough estimates . your oil press. sensor is most likely just old and not reading as it should . its easy to change , just above the oil filter . be careful with the plastic connector , old plastic tends to be brittle & cracks easy . good luck ....

 

I had said above in my original post, I also changed the oil pressure switch with a new ACDelco and also a Standard one (both gave the same readings) just to make sure it was reading correctly, so that is not the reason i don't think

 

You are using a thicker grade of oil bone stock right why would you go to a thicker oil? Your engine was engineered to use i believe 5w-30. I would use the grade the manufacturer calls for.

 

Through wear and tear clearances open up, leading some to use a thicker weight oil to make up the difference. If not using thicker oil to mask an underlying problem causing the oil pressure drop, then its a perfectly acceptable practice to help boost oil pressure from average wear and tear.

If something is seriously wrong, then the thicker weight won't do very much.

 

92 will be a roller cam, no real need to go rotella. It wont hurt to grab some decent 10W-40 for an oil change.

 

Run Rotella T6. Full synthetic, meets gas and diesel specs, frequently on sale at O'Reilly's for about $18 a gallon.

Low hot idle pressure with RP is something I have seen before.