So i've owned my '92 RS for a few months now, havent changed the oil myself yet although i did check it, just to make sure it was fine for the time being. The previous owner took pretty good care of it, and he said it was just changed when i bought it, and ive only driven about 2.5k so i was'nt too worried. I was gonna changed it today but just remembered that i neglected to ask the previous owner what type of oil he had been using.
I'm by no means an expert, so i was wondering if anyone had suggestions as to what type of oil i should use. The lo3 reads 74k, and at idle the oil pressure reads pretty low, although it jumps up while accelerating/cruising. It's in California and this winter temperatures have been from 20-70 F so far. I was just gonna put some 10w-30/40 in it. My only real concern is since i dont know what was in there, i dont know whether using a multi-weight oil with detergent could be detrimental if the engine had been using an oil without detergent. It's already running a little low on oil pressure, and once again since i dont know whether thats because of a lighter oil that may be in there or wear on the engine, i dont want to risk lowering the oil pressure even further by cleaning out old gunk caused by the possible use of oil without a detergent in it. Thanks for your help in advance.

 

I don't think the lighter oil would cause the drop in PSI. I say that because I ran 5w-30 in my 88's 305 and it had plenty of pressure even before dropping in a rebuilt 305 with a HV oil pump.

I'm unsure about the detergent issue but, if the previous owner was running sythetic and you switch to anything else or vice versa you can develop oil leaks. The reason being that the oils all have different swelling characteristics on your seals. Even changing brands can cause this to happen.


You might want to take a look at your oil pump pickup tube/screen inside of the pan. It could be off kilter or clogged up. I need to do this on my 92 because I'm having the same issue that you are. On mine though I'm fairly sure it's the pump as I've spun my engine up to 6000+ a few times recently and I don't recall the issue prior to that. I think you can drop the pan out with the engine still bolted down but, I honestly don't remember.

 

I switched to a synt. blend 10w 30 at 90,000 about a year and a half ago and I love it. I did not develope oil leaks but my engine was/is mechanically sound. It seems like I got a slight increase in power/performance.

 

Well that could be my problem, trying to prevent that. Anyone have any idea as to what would be the safest oil to use, not knowing whats currently in there.

 

Any API SJ/SL/SM rated oil will be fine. It's actually pretty hard to find a non-detergent oil these days.

10W-30 will be fine in California (unless you're up in the mountains).

Switching from synthetic to petroleum-based doesn't cause leaks. Mobil 1 back in the 70's & 80's had leakage/use problems. Other synthetics could cause leaks in higher mileage engines by desolving the crude left by petroleum oils that were aiding the sealing. With the mandated improvements in all types of oils with regard to deposits in the last 10-15 years, it isn't nearly the problem it was before.

If you decide to use synthetic, use Mobil 1, AMSOIL, Red Line, or Royal Purple. Anything else is a wannabe (that legally can't be challenged).

Some many myths, so little time. . .

 

What i was thinking about the whole deal, but since im no expert i figured being cautious was best until it came from the mouth of an expert. Thanks alot five, was gonna go buy a SL/SM 10w-30 today anyways, that certainly just put my mind at ease.

 

I would be willing to bet your oil pressure gauge is off. Way off. Hook up a mechanical gauge to check it, mine seldomly works and it stock. If oil pressure drops too low the switch will kill the fuel pump as a safety. BTW I use Valvoline 5w-30 and still haven't had a problem.

 

Went out and got some Mobil clean 5000 10w-30, and a Mobil M1-111 oil filter. Also ordered an Edelbrock open element air cleaner and a K&N air filter to match. Im excited to actual be doing something, not much, but its a start.

 

Mobil Clean is in the wannabe catagory. So are the AMSOIL XL series oils for that matter.

They're not "bad", but just not as good as the PAO formulas.

You know about the IAT and non-emissions-legality of the open element, right?

 

Know about the IAT, not much about the emissions area of the open element. Dont see how its gonna make too much of a difference. I live in california, which is obviously **** about emissions, but i dont have to pass smog for awhile. Enlighten me on the emissions issue, although i figure i can just put the stock aircleaner back on if i really need to.

 

That's all, you'll just have to put the stock air cleaner back on for inspection.