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Re: [GMCnet] Engine lubrication [message #355653 is a reply to message #355628] Sat, 13 June 2020 19:51 Go to previous messageGo to previous message
jimk is currently offline  jimk   United States
Messages: 6734
Registered: July 2006
Location: Belmont, CA
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Senior Member
This topic can go on till the cows come home as there is only a small
difference as to slight chang in viscosity.
Just use sun oil and worry about other more important things.

On Sat, Jun 13, 2020 at 5:41 PM James Hupy via Gmclist <
gmclist@list.gmcnet.org> wrote:

> Shafts and bushings are kept separated from each other by something known
> as "a fluid wedge" created by the shearing away of oils by the unequal
> speed of both surfaces. Viscosity has a bit to do with this, but I am not
> sure just how much. Experts have never, ever agreed on this. I used to run
> 10w-30 H.D. Valvoline Dino oil in my 403 in my Royale, and my low oil
> pressure at idle always bothered me. So I switched to 20w - 50 H.D.
> Valvoline Dino oil. Much higher now at 140,000 miles on the clock.
> Engines in current applications were manufactured with synthetics with
> low viscosity in mind. Their clearances are wayyy tightened up compared to
> our cast iron dinosaurs. They also rev a lot, lot higher. Over 2 1/2 times
> higher than our Oldsmobiles do.
> So, most of the writers for road and track and other similar
> publications tout synthetic oils, because the companies advertise heavily
> in their magazine. If you bite the hand that feeds you, you won't have a
> job very long. Synthetics do a bang up job in engines designed for them. No
> argument from me on that point.
> Like I have always said. Opinions Vary. I appreciate your viewpoint.
> Jim Hupy
> Salem, Oregon
>
> On Sat, Jun 13, 2020, 5:15 PM Larry via Gmclist
> wrote:
>
>> Here is an article entitled "Motor Oil Engineering Test Data". 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 THINNER 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.
>>
>> So, the above is all Just My Humble Opinion backed by a few facts that I
>> found on the Web. Other opinions will vary.
>> --
>> Larry
>> 78 Royale w/500 Caddy
>> Menomonie, WI.
>>
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502

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