The Stovebolt Site Forums The Shop Area Engine Shop 216 oil pressure

I own a 1948 Chevy truck with the original 216 engine. I was told the engine was completely rebuilt in 1985 and once finished, the truck just set until I got it a little over a year ago. When I received the truck the first thing I did was change all the fluids including the oil. Not knowing about 216 engines, I replaced the oil with 10-40 detergent. The truck has run great and the oil pressure runs about 6-8 pounds at idle and 15-16 while driving. This weekend I did maintenance again changing the oil only now using 30w non detergent as was suggested. After I finished, the oil pressure now shows 15 pounds at idle and pegs out at 30 pounds revving up. Now I didn't drive it due to the heavy rain. Any reasons why the drastic change in oil pressure?

First, you must realize that the stock oil pressure gauge, may or may not, be accurate. For the sake of discussion, let us
assume it is accurate.

The reason you have higher pressure is that you have gone from 10 weight oil to 30 weight oil. Both sets of readings sound just fine; factory literature indicates that 15 lbs is expected when warm and when driving. Factory literature also indicates you can use too heavy of an oil, especially in cold weather, and they caution against that. 30 weight oil this time of year in TX should be fine.

The other issue is detergent vs non-detergent. If the engine was rebuilt and used little since, it should not have much sludge, so I would tend to use the detergent oil with it's modern additives from now on.

Kent

That's for the help. So with the 30w and if the pressure gauge stays pegged at 30 lbs when driving, that doesn't necessarily mean there is a problem? I didn't get to drive it so it might drop after heating completely up.
As you know, we never get cold in Houston. When it gets cooler, what oil weight would be appropriate?

With correct oil clearances and an accurate pressure gauge, 15 at idle and 30+ at cruise RPM is excellent. Back when those engines were new, most people used 30 weight in the summer, and switched to 20W-20 in the winter. I'd definitely recommend HD 30 (detergent) oil instead of non-detergent. The non-detergent oils available today are way down in quality, mostly intended for getting a few more miles from worn-out engines that burn or leak so much oil that oil changes aren't necessary. "Fill it up with oil and check the gas!"

If you want to use a multi-grade oil for some reason, 15W-40 Diesel rated oil would be a good choice.
Jerry

Thanks!