[GMCnet] Engine lubrication

[tom geiger via Gmclist]

So was watching a episode of “Roadkill” and they had purchased a old mazda pickup truck with a 455 in the bed of the truck. If you’ve ever watch
the show, these Frankenstein vehicles are the basis of show. Anyhow one of the host commented that he was not excited about the 455, said it was one
of the worst engines. Called it a boat anchor. I did some research and found some criticism on the way it leaves the bottom end of the engine dry of
oil when run at high rpm for duration of time. What do you guys do to help manage this?

Thanks,
TG

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[John Wright via Gmclist]

Tom,

First of all these guys on these show have no respect for equipment. They probably buzz the 455 in the truck at a high rpm as a guess 4500 +rpm and beat the crap out of it (tech term). Some 455 have be built for racing and that does require special prep on the bottom end and oil system. Oil weight also makes a difference as I have alway run a 15/50 or 20/50 oil over the years starting with dino oil and then as semi synthetic and then a full synthetic in the last few years. Remember that the 455 was originally spec’ed to use a 10/30 or straight 30 weight oil.

The motor in the GMC motorhome depending on the final drive, tire size and speed never goes over 3000 or so RPM for any extended period of time. Typically if you have a 3.07 gear you’re only running 2350 rpm at 70 ish mph. The 3.55 gear runs 2650+/- at 64/65 mph and 3.66 ratio is typically about 2875 +/- at 63/64 mph. I have had experience in all three ratios. I have run all day long with the 3.66 final at 3000 rpm when I needed to make miles for years and have never had an engine issue and or had oil pressure fluctuations ever in the 20+ years and all my engines weather a 403 or 455/461. My oil pressure has run in the motors that I have use has been right at 50 psi at speed. The 455 was used for years to power big irrigation pumps for hours and hours.

J.R. Wright
GMC Great Laker MHC
GMCGL Tech Editor
GMC Eastern States Charter Member
GMCMI
78 GMC Buskirk 29.5’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan

[Tom McManus via Gmclist]

The 455 was used in a lot of Jet Boat applications. A trick the boat guys came up with was to tap into the oil return on the side of the heads and run
a direct line down to the oil pan.
--
Tom McManus
1977 Royale

Chesapeake VA

[Tom McManus via Gmclist]

I was just replying to the question. A 455 can't return oil over 4500rpm for any extended length of time without it pooling in the heads. The return
line was the trick to getting oil back to the pan. My first experience with a 455 was in a Marlin jet boat I renovated many years ago. I ran it at
4800 for lengthy periods with out oil pressure loss. Scary thing. 85mph at 4800. I could shoot a rooster tail 80ft in the air.
http://www.gmcmhphotos.com/photos/member-galleries/p67346-jet-boat-455.html

--
Tom McManus
1977 Royale

Chesapeake VA

[Johnny Bridges via Gmclist]

The jet boats (Buelher TurboCraft??) at high revs sustained, and they seemed to survive it. And, pumps and boats are analogous to aviation engines in
this regard, as opposed to ground vehicle service. Constant speed and load,versus variations in both on the road.

--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

[tom geiger via Gmclist]

Yep understand. He was a younger guy and may not understood how tough those engines were built back then. Good to know it will be fine. Just getting
it over to my house to do some projects on it and one of the first items is change the oil.

[James Hupy via Gmclist]

Tom, just keep the revs under 5500, and you should be just fine. Let's see?
5500 rpm with 3:07 final drive and stock sized tire circumference, pencils
out to not quite 120 mph. Good luck getting her home!
(VERY BIG GRIN)
Jim Hupy
Salem, Oregon

[Jim Kanomata via Gmclist]

These engines were not designed for constant Hi revs .
People in the know made sure the return of the oil from the head drained
down easily and also restricted the amount of oil at the push rods.

--
Jim Kanomata
Applied/GMC, Newark,CA
ji...@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502

[John R. Lebetski via Gmclist]

J.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 gearings and heat kills soft bearings
--
John Lebetski
Woodstock, IL
77 Eleganza II

[James Hupy via Gmclist]

For the application of the slow engine speed ranges that our coaches
operate in, 1800 - 3200 rpm. 20w - 50 is a good call. Need a bit higher
viscosity because of high bearing loads, and large throttle openings at
relatively low rpms. Lots of heat in those piston crowns.
Jim Hupy
Salem, Oregon

[Jim Kanomata via Gmclist]

WE know this, the synthetic oils are considerably better than the
conventional.
Yes, it can leak more, but your getting more protection and dirtying your
drive way.

--
Jim Kanomata
Applied/GMC, Newark,CA
ji...@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502

[tom geiger via Gmclist]

Ok, sounds like I want to go get some synthetic for the oil change.

Thanks all,

[John R. Lebetski via Gmclist]

James Hupy I disagree. Viscosity is the resistance to flow. With high heat loads you want lower viscosity oil as more flow over the bearings
transfers more heat then on to remove it at the oil cooler. Viscosity and film strength are not the same thing.

--
John Lebetski
Woodstock, IL
77 Eleganza II

[Larry via Gmclist]

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.

[James Hupy via Gmclist]

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 <gmc...@list.gmcnet.org>
wrote:

[Jim Kanomata via Gmclist]

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.

--
Jim Kanomata
Applied/GMC, Newark,CA
ji...@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502

[Grant Schaffer via Gmclist]

So my question is synthetic oils cause your engine to leak?
--
1974 GMC Sequoia 26'

[Jim Kanomata via Gmclist]

Since the cold viscosity is thinner, it can leak more. Your not seeing the
leak as it is minor and the syn oil can cause more leakage at where it is
already leaking,

--
Jim Kanomata
Applied/GMC, Newark,CA
ji...@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502

[Matt Colie via Gmclist]

Husker92592 wrote on Sat, 20 June 2020 12:10

> So my question is synthetic oils cause your engine to leak?

Grant,

The simple answer is NO.
Unlike many situations, I do not know how this got started. While often times the dynamic viscosity is no different than specified, because the
synthetic lubricants stay where they are distributed better, they often lead to an apparently higher lube oil consumption. This is a result of their
presence on the combustion chamber walls.

I believe this may have started with owners changing to synthetic and them being more conscious of the 6$/quart than they were of the 2$/quart and
that is understandable.

My recent overhaul has only leaked where I made some mistakes and took too long to correct them. (Shortly after restarting, she was loosing a quart
every four hours until I got in there to find and make up the cooler line as it should have been.)

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

[Johnny Bridges via Gmclist]

Just finished setting up the injector so it idles correctly. While I was fiddling with it, I set the max RPM to 4500. Should I have a problem on a
hill on S, I'll turn it up a bit - but not much :)

--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

[Grant Schaffer via Gmclist]

So,
Reason for the question and I will keep in real simple, ME being a dealer for synthetic oils for a long while now, al beit almost every car today
requires synthetics, where this comes from is switching to synthetic and switching back to dyno oil "can" cause old seal to shrink.

if everything is correct and one is adding to a new rebuilt engine or existing old seals, you might want to think of replacing the seals. In no way am
I suggesting these are things you should so but Synthetic oils have one benefit in that they "can" cause swelling or expansion of old seal which is
the opposite of leaking.

for all those who like Dyno oil then great keep using them. in some parts of the county we dont have the advantage of benefiting from cheap anything.
quite honestly I am purchasing synthetics cheaper than Dyno oil. FYI oil does not go bad its the additives that have a shelf life. This is for any oil
you use.

In General for the heat and abuse we place on out coach engines you want to change your oil and filter every 5000 miles anyway. Can you go longer on
Synthetic yes but that is each owners personal preference.

--
1974 GMC Sequoia 26'

[Richard Michelhaugh via Gmclist]

JohnL455 wrote on Sat, 13 June 2020 13:02

> J.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

[Johnny Bridges via Gmclist]

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

[Carl Stouffer via Gmclist]

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

[Richard Michelhaugh via Gmclist]

Carl S. wrote on Wed, 12 August 2020 22:47

> 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 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

[roy keen via Gmclist]

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

[Mike Hamm via Gmclist]

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