Question: Oil pressure

[JOHNNYB]

Hi, i had vette out yesterday (messing with tps ) but my question is eventually the car got to operating temp and the oil pressure was at 24lbs at high idle at 1000rpm because of tps. But even when revd the pressure did not change more than a few lbs and it usually gets to about 45-50 around town.

 

[tonylong]

My '89 is usually at mid-20's with medium idle - 6-700. It'll jump to 40's-50's when I hit it. It's always done that, I have 70,000 miles on her now. No smoke or oil consumption.

 

[TedC]

I've been documenting oil pressures on my 60K 1989 L98 over the years. All readings are using the cluster which are not always 100% accurate vs. actual pressures. However, the posted results are using the same oil pressure sending unit and only AC PF454 filters.
5W30 Pennzoil Conventional: 12 lbs at 230 degrees F in drive, 45 lbs at 2000 in park
5W30 Mobil 1: 15 and 48
5W30 Penzoil Conventional High Mileage: 16 and 50
10W30 Penzoil Conventional: 15 and 45
10W40 Valvoline Conventional: 18 and 58
Pressure readings are higher than posted at lower temps. My favorite Chevy dealer said that it is common for a distributor driven oil pump like that used on a L98 to post 10-20 lbs of oil pressure readings at idle when hot (just before the fan kicks in). Starting in 1989, Chevy actually increased the cold crank time a few seconds in order for the L98 to build more oil pressure before firing up. I have not seen any measurable differences in MPG, even when using the thicker 10W40 oil.

 

[boomdriver]

Thats about average. I was overly cautious when my last motor was built and demanded a high-pressure pump be installed. Cold it bottoms out at 80lbs idle and sits around 55 to 70 hot at 1500 rpm or higher. Idle will run as low as 20 with 15/50 Mobile-1 at 220+degrees.
High Vol is better than high pressure, but the entire engine has to be set up for high vol oiling otherwise the fancy pump is a waste of money. Clean oil is more important than anything else.

Having built various engines over the years, I know that 80% of internal wear comes at cold start up, so I run Pro-Long as well. I have seen the results of that and believe in the product. Even a dose of marvel-mystery oil in the gas for extra top-end lube when I know that I might be pushing the limits a bit, such as racing or high rpms.