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Re: Engine lubrication [message #357651 is a reply to message #355638] |
Tue, 11 August 2020 20:50 |
rickmike
Messages: 252 Registered: September 2011 Location: United States
Karma: 0
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JohnL455 wrote on Sat, 13 June 2020 13:02J.R. If GM says 10W-30 then what is your logic that 20W-50 is “better”? Seems it would exasperate the gravity drain back issues. Most builders today don’t like heavy oils as they pull less heat from bearings and heat kills soft bearings
The oil GENERATES the heat in hydrodynamic bearings The more viscous the oil, the more heat is generated in the bearing and the thicker the oil film that separates the shaft from the shell(up to a certain point). And yes, it carries the heat away too.
They use lighter weight oils today to generate less heat thus less friction losses. The bearings are designed for the lower viscosity oil.
Rick Michelhaugh
1974 26' Canyonlands
aka "The General"
Clinton, TN
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Re: Engine lubrication [message #357655 is a reply to message #355626] |
Wed, 12 August 2020 07:29 |
jhbridges
Messages: 8412 Registered: May 2011 Location: Braselton ga
Karma: -74
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In the 70s, I spoke to guys at airshows. Most of them, and they said the racers as well, used reprocessed oil in the airplanes. They weren't worried about additives, the oil was changed every day at least, and for the racers every flight. They said the oil was 'oilier' in that it had been refined three times - initially, in the engine, and again at the reprocessor's. This supposedly breaks down the molecules even smaller, giving better lubrication. That was their story anyhow.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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Re: Engine lubrication [message #357679 is a reply to message #355936] |
Wed, 12 August 2020 21:47 |
Carl S.
Messages: 4186 Registered: January 2009 Location: Tucson, AZ.
Karma: 13
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The machine shop in Tucson that did the work on my 455 (Larry's engine and Marine) said that, due to the large size of the main journals on the 455 crankshaft, they set the clearances for 20W50 oil. I'm not totally clear on the reason why, but it has to do with getting enough oil in those large diameter bearings. I broke it in with 15W40 Rotella, but imediately switched to Valvoline 20W50. I would be comfortable going back to the 15W40, but think maybe the 20W50 is a better choice for me in Southern AZ, where I am often driving the coach in 100 plus degree temps, at least during the Summer.
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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Re: Engine lubrication [message #357702 is a reply to message #357679] |
Thu, 13 August 2020 23:45 |
rickmike
Messages: 252 Registered: September 2011 Location: United States
Karma: 0
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Carl S. wrote on Wed, 12 August 2020 22:47The machine shop in Tucson that did the work on my 455 (Larry's engine and Marine) said that, due to the large size of the main journals on the 455 crankshaft, they set the clearances for 20W50 oil. I'm not totally clear on the reason why, but it has to do with getting enough oil in those large diameter bearings. I broke it in with 15W40 Rotella, but immediately switched to Valvoline 20W50. I would be comfortable going back to the 15W40, but think maybe the 20W50 is a better choice for me in Southern AZ, where I am often driving the coach in 100 plus degree temps, at least during the Summer.
I'd like to see how he determined clearances for the 20W50 oil! Since I studied tribology, I know that it is a pretty complicated process to properly design a bearing for a particular weight oil.
Rick Michelhaugh, ME
1974 26' Canyonlands
aka "The General"
Clinton, TN
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Re: Engine lubrication [message #360510 is a reply to message #355906] |
Fri, 04 December 2020 11:29 |
roy1
Messages: 2126 Registered: July 2004 Location: Minden nevada
Karma: 6
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I would not consider running a big block olds more then 4500 I think 4000 would be my limit not worth the chance of spinning a rod bearing.I also wouldn’t consider o-20 oil over 15 -50 in our old tech engines. A lot of stuff you read these days is for newer tech engines but that’s just my opinion.
Roy Keen
Minden,NV
76 X Glenbrook
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Re: Engine lubrication [message #360511 is a reply to message #360510] |
Fri, 04 December 2020 11:39 |
mghamms
Messages: 466 Registered: March 2016 Location: Ware, Massachusetts
Karma: 2
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I use Mobil One 15-50 and change with filter about every 2000 miles.
When I first got it I changed the oil, whatever I had cheap, and filter every 200 miles to get the crud out.
Hopefully cheaper than a eventual rebuild.
Also every year I drain about 3 quarts of ATF and refill with new.
And suck the master brake cylinder dry and refill.
1977 Kingsley 455 as stock as it gets except lots of Ragusa parts
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