Visual of oil viscosity
- Thread starter D2Cat
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Odd.... I'd expect both 5W to be the same at room temperature. Got to be something off with that test.
A better test would be a drip test. A quart and a tiny hole for each sample and time to drip a quart. Oil rating is viscosity, 'thickness'/ability to flow not film strength. Do this test in a freezer, then again at room temperature then again heated to 180f.
A better test would be a drip test. A quart and a tiny hole for each sample and time to drip a quart. Oil rating is viscosity, 'thickness'/ability to flow not film strength. Do this test in a freezer, then again at room temperature then again heated to 180f.
in terms of engine oil, viscosity refers to how 'well' it flows.
Remembering that modern engines have much smaller oil flow channels and galleys, and often much longer distances from the oil pump too.
so when the manufacturer says use 0w40, it's for a reason and not so much MPG or emissions as it is to make the engine last longer. A cold engine at startup needs oil pressure to everything as soon as possible and 0w40 will achieve that goal faster than 20w50 will.
There's a lot more to it but that's the very basics. Use what the mfg says.
Remembering that modern engines have much smaller oil flow channels and galleys, and often much longer distances from the oil pump too.
so when the manufacturer says use 0w40, it's for a reason and not so much MPG or emissions as it is to make the engine last longer. A cold engine at startup needs oil pressure to everything as soon as possible and 0w40 will achieve that goal faster than 20w50 will.
There's a lot more to it but that's the very basics. Use what the mfg says.
Of course there are exceptions like the GM 6.2 where the thin oil has destroyed many engines. GM updated the owners manual and the oil cap to show thicker oil.
RCW
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BX2360, FEL, MMM, BX2750D snowblower. 1953 Minneapolis Moline ZAU
I had only heard of 6.2l issues generically - - no details.
Looked it up today after seeing your reply.
Sounds like root cause gets back to the 0w-20 motor oil and AFM.
Heard of similar problems with earlier 5.3's but not to the extent they're seeing with the 2021-2024 6.2's.
Right or wrong, I drive my 2017 5.3 in "Manual 5," which locks out the AFM. Probably hasn't run on 4-cylinders for 500 miles in 8 years.
I actually think I get better MPG on hilly two-lane rural roads. 20+mpg is normal in the summer. 16-18 in the winter.
that engine will not stay together on any oil. Poorly designed, or should I say it had a decent design but poorly executed. GM knows this. They're trying to shift the liability to the owners. It's what they've done for years and why I do not buy GM vehicles, which is unfortunate because there are things I do like about them, well some of them. It's a matter of principle, that's all.
It was quite a few yrs ago on Utube a 'engineer' did a oil test. At the lab they had a freezer that was at some crazy temp like -50* below F.
He had five or six quarts of different brands of oil. Put them in the freezer for a number of hours. Then had a board the clamped each bottle and flipped over to drain the oils. What I remember about the test was the Walmart oil. Even after five minutes not one drop came out of the bottle. Lol
He had five or six quarts of different brands of oil. Put them in the freezer for a number of hours. Then had a board the clamped each bottle and flipped over to drain the oils. What I remember about the test was the Walmart oil. Even after five minutes not one drop came out of the bottle. Lol
RCW
Well-known member
Lifetime Member
Equipment
BX2360, FEL, MMM, BX2750D snowblower. 1953 Minneapolis Moline ZAU
As a kid, I had a car that burned more oil than gas.
Had to add a quart 1-2x/week.
I've added motor oil at -20-30 degrees F.
It was very thick, like cold molasses thick.
Had to add a quart 1-2x/week.
I've added motor oil at -20-30 degrees F.
It was very thick, like cold molasses thick.
I've got a '21 Trailboss with the 6.2 and got a letter from GM telling me to wait for further notice. I suppose they didn't have their ducks in a row but wanted to let owners know. Still waiting LOL
I've had no issues with mine. Performs well and does what i need it to. AFM doesn't get used much as I live in the mountains.
Average MPG is 18-19. Was 22ish till I put bigger tires on it.
I've had no issues with mine. Performs well and does what i need it to. AFM doesn't get used much as I live in the mountains.
Average MPG is 18-19. Was 22ish till I put bigger tires on it.
I had a '68 Ford Fairlane 289 for my first car that was a "fill the oil, check the gas" almost kinda engine, remember the STP oil additive that came in a metal can, that was as thick as molasses? I ended up running about a 50/50 mix in it!
Kind of like trying to get Lucas down a funnel in winter. Gotta mix that thick stuff with some oil to get it all down LOL
a quart a couple times a week? I got that beat.
had an 82 El Camino, 3.8L Chevy (not Buick, you could have them both ways) 90 deg V6. The word "TURD" didn't describe it. I absolutely HATED that thing but it did have some usefulness at the time.
For about 4 months I was putting a gallon in every day. I had no (zero) money to fix it, didn't have time to fix it, because I lived alone, no neighbors, no family, very few friends and the ones I did have knew NOTHING about cars (ladies mostly), so it was all me. Coworkers shyed away from it too and I don't blame them. LUCKILY for me, we had ordered kubota 15w40, usually got it by the gallon but for some reason they got a free drum and said "use it up on whatever". So I filled a milk jug at 5:30 every day, dumped about half of it into the "cruck" (or was it a cark? ), drove home-about 30 min drive, sat at the house unless someone came to pick me up....the house was a disaster, needed everything fixed (roof siding driveway walls hvac etc) but it was CHEAP RENT. I was making about $240 a week on my paycheck and that old cark or cruck junk-a-mino ate up a lot of it in gas. Plus utilities, rent, cruck payment (weekly), food, women, you know, the important stuff...so as long as I could get free oil, fixing it was on the back burner until I could get another vehicle, which I did...and moved OUT of that place, in the same day. I sold them the junk-a-mino for $250 after I rolled it and the new owner was asking me questions...."how much rust"...NONE, it will NEVER rust (it leaked a gallon a day).
the leak was so bad that if I filled it at 0730 and drove it to work, then drove it home it would be OUT of oil by the time I started climbing the hill that the house was on. So I just put the half gallon in at 0730, the other half at quitting time and do it all over the next day. I never bothered to actually isolate where it was leaking from but I think it was probably a galley plug in the back of the block-inside the bellhousing, and I had no way to pull the transmission to do it, nor enough money to pay someone.
Bought a 91 Ranger (v6 2wd) to replace it. Great truck. Small, but I don't know how many hundreds of thousands of miles I put on it without a single issue. Sold it to my brother, who wrecked it the day after he bought it (not his fault though).
had an 82 El Camino, 3.8L Chevy (not Buick, you could have them both ways) 90 deg V6. The word "TURD" didn't describe it. I absolutely HATED that thing but it did have some usefulness at the time.
For about 4 months I was putting a gallon in every day. I had no (zero) money to fix it, didn't have time to fix it, because I lived alone, no neighbors, no family, very few friends and the ones I did have knew NOTHING about cars (ladies mostly), so it was all me. Coworkers shyed away from it too and I don't blame them. LUCKILY for me, we had ordered kubota 15w40, usually got it by the gallon but for some reason they got a free drum and said "use it up on whatever". So I filled a milk jug at 5:30 every day, dumped about half of it into the "cruck" (or was it a cark? ), drove home-about 30 min drive, sat at the house unless someone came to pick me up....the house was a disaster, needed everything fixed (roof siding driveway walls hvac etc) but it was CHEAP RENT. I was making about $240 a week on my paycheck and that old cark or cruck junk-a-mino ate up a lot of it in gas. Plus utilities, rent, cruck payment (weekly), food, women, you know, the important stuff...so as long as I could get free oil, fixing it was on the back burner until I could get another vehicle, which I did...and moved OUT of that place, in the same day. I sold them the junk-a-mino for $250 after I rolled it and the new owner was asking me questions...."how much rust"...NONE, it will NEVER rust (it leaked a gallon a day).
the leak was so bad that if I filled it at 0730 and drove it to work, then drove it home it would be OUT of oil by the time I started climbing the hill that the house was on. So I just put the half gallon in at 0730, the other half at quitting time and do it all over the next day. I never bothered to actually isolate where it was leaking from but I think it was probably a galley plug in the back of the block-inside the bellhousing, and I had no way to pull the transmission to do it, nor enough money to pay someone.
Bought a 91 Ranger (v6 2wd) to replace it. Great truck. Small, but I don't know how many hundreds of thousands of miles I put on it without a single issue. Sold it to my brother, who wrecked it the day after he bought it (not his fault though).
Of course you can see alot of stuff on the internet.
There's a guy on YouTube a oil engineer(his claim) and one statement he had made, made complete sense to me.
"If your oil needs some sort of additives added to it, then your using the wrong oil". Save your money.
There's a guy on YouTube a oil engineer(his claim) and one statement he had made, made complete sense to me.
"If your oil needs some sort of additives added to it, then your using the wrong oil". Save your money.
A stupid question: we are dealing mainly with water cooled engines (air cooled engines are a different matter, of course). So the temperature, when running, is regulated by a thermostat.
That means all those different oil viscosities only matter at startup until the engine is heated up. Or am I missing something?
That means all those different oil viscosities only matter at startup until the engine is heated up. Or am I missing something?
No, i don't think your missing anything.
I'd have to look at my owner's Manuel but I think it has a chart. Temps _____to _____
Use 15w 40, temps like Fairbanks in January use oil ______. I've always run rotella 15w 40 year round here. When it's really cold I plug my tractor in for a hour before starting. And had no issues.
I'd have to look at my owner's Manuel but I think it has a chart. Temps _____to _____
Use 15w 40, temps like Fairbanks in January use oil ______. I've always run rotella 15w 40 year round here. When it's really cold I plug my tractor in for a hour before starting. And had no issues.
You are missing something but its pretty nuanced.
There is property called High Temperature High Shear (HTHS) viscosity. That property is the dynamic viscosity of the oil at 150C when operating under high shear conditions. HTHS is measured using a rotary viscometer and simulates the conditions inside journal bearings when the engine is running. This is the viscosity that actually maintains the hydrodynamic oil film that lifts the bearing off the journal surface.
The SAE Viscosity Grade Standard Standard (J300) specifies different HTHS minimums for different grades - see table below. Oils with higher HTHS are "better" at protecting bearings operating under high speed heavy load conditions and is the main reason that for decades 15W40 was the grade of choice for heavy duty diesel engine oils. That has changed with tighter engine tolerances and the development of better base oils - e.g synthetics.
Dan
You are missing the fact that the oil pan temperature isn't controlled and that will have some effect.
Thank you Dan and lynnmor,
yes, of course the oil temperature is still changing a bit depending on outside temperature.
And modern engines with tighter tolerances I had forgotten; I have only old vehicles
yes, of course the oil temperature is still changing a bit depending on outside temperature.
And modern engines with tighter tolerances I had forgotten; I have only old vehicles
I should have said clearances rather than tolerances. If you reduce the oil clearance in a journal bearing you get an increase in the oil film pressure. That allows you to use an oil with a lower HTHS.Thank you Dan and lynnmor,
yes, of course the oil temperature is still changing a bit depending on outside temperature.
And modern engines with tighter tolerances I had forgotten; I have only old vehicles
Oil temperature inside a journal bearing is much higher than sump temperature.
Dan