| Re: [GMCnet] Re: Oil Pressure Poll [message #366559 is a reply to message #366556] |
Tue, 07 September 2021 20:15   |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma:
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The machine work on my engine was done at Larry's Engine and Marine here in Tucson. Larry has extensive experience with Olds 455 engines, having built literally hundreds of them over the years for jet boat and hot rod applications. He understood the motorhome application and provided machine shop and parts services accordingly. The bearing clearances were set up specifically for 20W50 oil due mostly to the giant size of the main journals on the crankshaft of a 455. This was Larry's recommendation. I had already been running 20W50 oil, at Jim Bounds' suggestion before the rebuild.
Last year, about this time, we embarked on a 3500 mile trip to The Grand Tetons, Yellowstone, Devil's Tower, Rapid City, and back through several Wyoming and Utah national parks and monuments. Right before that trip, I had decided to experiment with 15W40 Rotella oil instead of the Valvoline 20W50 I had been using. I noticed my oil pressure running lower than usual as a result and stressed about it for most of the trip. I changed back to the 20W50 and the oil pressure (on the stock gauge)returned to what it had been before. I won't run anything in it but 20W50 again.
Maybe you need to run a heavier oil in it, at least 15W40, if not 20W50.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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