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Re: Engine lubrication [message #355649 is a reply to message #355626] Sat, 13 June 2020 19:14 Go to previous messageGo to previous message
Larry is currently offline  Larry   United States
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
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Here is an article entitled "Motor Oil Engineering Test Data".

https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

It is a long read with lots of repetition. Tests were run on 239 different oils or oils with after market additives. Oils are ranked by their ability to resist wear. An interesting read as most of the higher ranked oils are of relatively low viscosity. 5w30's, 0w20's etc. Here is a copy/paste of a section written about viscosity.


SECTION 2 – MOTOR OIL VISCOSITY SELECTION

THE BENEFITS OF USING THlINNER OIL:

• Thinner oil flows quicker at cold start-up to begin lubricating critical engine components much more quickly than thicker oil can. Most engine wear takes place during cold start-up before oil flow can reach all the components (the longer an engine has been sitting, the more of a concern this becomes), and during warm-up while the oil is still thicker and not flowing as freely as it does during normal hot operating temperature. So, quicker flowing thinner oil will help reduce start-up and warm-up engine wear, which is actually reducing wear overall.

• The more free flowing thinner oil during cold start-up and warm-up, is also much less likely to cause the oil filter bypass to open up, compared to thicker oil. Of course if the bypass opened up, that would allow unfiltered oil to be pumped through the engine. The colder the ambient temperature, and the more rpm used when the engine is cold, the more important this becomes.

• Thinner oil also flows more freely when fully warmed-up to normal operating temperatures. And oil FLOW is lubrication, but oil pressure is NOT lubrication. Oil pressure is only a measurement of resistance to flow. Running thicker oil just to up the oil pressure is the wrong thing to do, because that only reduces oil flow/lubrication. Oil pressure in and of itself, is NOT what we are after.

• The more free flowing thinner oil will also drain back to the oil pan quicker than thicker oil. So, thinner oil can help maintain a higher oil level in the oil pan during operation, which keeps the oil pump pickup from possibly sucking air during braking and cornering.

•The old rule of thumb for desired oil pressure, that we should have at least 10 psi for every 1,000 rpm, pertains to, and is highly recommended for High Performance and Racing engines. Engine bearing clearances are primarily what determines the oil viscosity required for any given engine. (NOTE: Viscosity does NOT determine an oil’s wear protection capability, like many people think. Wear protection capability is determined by an oil’s additive package, which contains the extreme pressure anti-wear components. That is why 5W30 oils can perform so much better than thicker oils in my wear protection capability testing). But, whatever the bearing clearance, for High Performance and Racing engines, it is best to run the thinnest oil we can, that will still maintain at least the old rule of thumb oil pressure, even if that means using a high volume oil pump to achieve that. A high volume oil pump/thinner oil combo is much preferred over running a standard volume oil pump/thicker oil combo. Because oil “flow” is our goal for ideal oiling, NOT simply high oil pressure. So, one of the benefits of running a high volume oil pump, is that it will allow us to enjoy all the benefits of running thinner oil, while still maintaining desirable oil pressure.



I have been using two of the higher ranked oils on this list in my personal vehicles including our GMC. I have been very happy with the performance of 0w40 Mobile 1 (ranked #7) used in my Cad 500 powered GMCMH. I am thinking about going to (ranked #4) 5W30 Quaker State Ultimate Durability, dexos 1 – Gen 2, API SN “Plus”, synthetic (green bottle), because of it's higher wear rating. Both of these oils are available at local Walmarts at very reasonable pricing.

Just another way of looking at things. So, the above is FYI and all Just My Humble Opinion backed by a few facts that I found on the Web. Other opinions will vary.

Larry Smile
78 Royale w/500 Caddy
Menomonie, WI.

[Updated on: Sat, 13 June 2020 19:24]

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