Great video, explains all the basics in a very clear manner.
Use what is stated in your owners manual!
Yep, both my V8 truck and my turbo-4 car take a syn-dino blend, nearly 70,000 miles on the truck, 5W-20 oil. So far have only added one pint of oil, that was after much mountain driving locking out top three gears for steep downgrades.
When only dino oil was around I had a 455 Buick, living in Florida, I chose 20w-50 due to our normally high temperatures. Had a cold snap, overnight temperature dropped to the low 30s, went to start the Buick, very sluggish, when it did start, zero oil pressure. Did not get oil flowing until the engine started to get warm.
In the video they did say you can safely use a lower first number since. So if oil recommended for you car is 5W-30 - you can safely use 0W-30. But if the oil recommendation is 0W-30 - you may not be able to safely use 5W-30.
The last number - Not a good idea to go to a lower number since it may not offer the same protection at operating temps. If recommended oil is 0W-40 then switching to 0W-20 could harm your engine. Going up may be acceptable, but not recommended.
One thing he pointed out early in the video was that the main reason for these thinner oils was to meet Cafe’ numbers. So, I’m sure there’s a range many vehicles can safely run at. My wife’s 07 Lexus oil recommendation is 5W-30. My 14 Highlander (same engine) is 0W-20. I’ve been using 0W-30 in both for over a few years. Easier for me to just keep one oil around.
To my knowledge no 0w-30 offered in 1972.
I don’t think the curve in the graph from the video is correct. With multi viscosity oils, there is a flat spot in the curve at the temperature where the viscosity modifiers activate. But I’m not referring to true sythetic oil which can be different.
If 10W30 is specified when 5W30 was also available, it’s probably because 5W30 does not have sufficient temperature and shear performance. Today 5W30 might outperform the 10W30 from 3 decades ago so it is acceptable to use it.
I started another thread about this, but people who have engines with tight tolerances have noticed their oil pressure drop not too long after changing the oil with these cheap 5W30 and 10W40 as the oil breaks down from shearing. 10W40 eventually becomes 10W10 + sludge.
Lots of stories, no facts. “Sludge”? We’d have engines failing all the time. Not happening. Please post a plot of the “flat spot” in oil viscosity. The video’s plots are instructive, not exact, and the basic relationships depicted are correct.
And your degree in engineering is from what university?
The plot may not be 100% accurate, but it is very accurate, and very informative.
And your evidence is? Please point to the engineering white paper or scientific study that backs up that nonsense.
Now that I think about it, that statement is incorrect. The base oil viscosity is dropping with increasing temperature, regardless of what the viscosity modifiers are doing. All viscosity vs. temp plots I have found show decreasing viscosity with increasing temperature for all oils, single or multi-weight.
The university of [[[ NONSENSE ]]].
That’s what I see too. I remember coming across a chart once that showed where 10W40 or such transitioned from following the 10 weight line to the 40 weight line. Can’t find it now or maybe my memory is incorrect. A lot of those graphs might be for synthetic oils that are different.
This would be a good experiment. I just need a kit to be able to measure the viscosity at home.
Not now, but GM had a lot of engine failures starting in 1975 due to oil sludge cause from a combination of 10w40 oil, 7500 mile oil change intervals and higher operating temperatures due to new smog controls.
One reason you didn’t see much about it was that the engines didn’t sludge up until about 40k miles, so they were out of warranty. The sludge mostly built up under the valve covers and didn’t affect operation until it got bad enough to plug the oil return holes.
People blamed it on Quaker State but it wasn’t Quaker States fault. Their reputation never fully recovered though. I cleaned quite a few of these engines of the sludge.
It WAS Quaker State and Penzoil. That time period was the nationwide introduction of unleaded gas. Unleaded gas burns a lot hotter then leaded. It was also the time when many cars were downsizing and more and more 4-cylinders were on the road. Pennsylvania crude oil didn’t handle these higher temperatures well. I was putting myself through college as a mechanic during that time period. This small garage was seeing many engines starting to burn oil after only 40k miles. And these were our steady oil change customers. We tore down a few of these engines and found sludge buildup on the rings, valve covers and the oil pan. We used nothing but Quaker-State. The owner had other friends in business seeing the same thing…but there were a few that weren’t. Those businesses weren’t using a Pennsylvania crud oil. One was using Castrol exclusively. Owner switched to Castrol.
Since then Quaker-State is no longer a Pennsylvania crud oil. Their oil is EXCELLENT. But you can’t deny they had a problem in the 70’s.
I’m going to have to disagree with you on that. It was the viscosity improvers (VI’s) that were causing the oil to coke at lower temperatures. But you had one experience, I had another. Myself at that time, I only used Valvoline.
I had a problem with carbon buildup in my 1978 Oldsmobile Cutlass with the 260 V8 engine. It would ping loudly under even moderate acceleration. About once a month, I would add a can of Casite Engine Tuneup to a tank of gasoline and take the car out on the interstate, put the transmission in a lower range, and run the car at 65 mph. The black smoke would billow out the exhaust pipe for about half a mile. When the black smoke let up, I would shift into “Drive” and the ping would be gone.
I heard on the Cartalk radio show that the viscosity improvers in 10W-40 could cause the problem. The owners manual for my Oldsmobile specified either 10W- 30 or 10W-40. I had been using 10W-40, thinking it gave better engine protection. I switched to 10W-30 and the pinging under acceleration was gone and I never had to add Casite to the gas tank and take the Oldsmobile out on an interstate carbon blowout. I never had to add oil between 3000 mile oil changes and I put 240,000 miles on the car before I sold it. I put whatever brand of oil I could buy on sale.
In the engine in my push lawnmower, I had used straight 30 weight as recommended in the owners manual. After 25 years the engine burned oil so badly I fogged for mosquitoes while I mowed. I switched to full synthetic 10W-30 and the oil consumption was reduced 75%. I got three more seasons from the mower before the oil consumption went back up.
As with anything it seems, the reality is always way more complicated than people tend to boil things down to. It makes it easier to understand but it is not technically correct. VIs don’t “turn on” they are always actively changing. And there is far more to how they work than the simple coil analogy. Not only is there a thermally induced physical change, there are chemical interactions at play. The whole story gets even more complicated when different polymer chains are used together. Here’s a great article on the topic-
Most likely over heating due to grass build up in the cooling fins!
Thanks for the article Twin Turbo!
I cleaned the fins every month during mowing season. I changed the oil at the beginning of each season, replaced the spark plug, sharpened the blade and replaced the air filter. Changing to synthetic oil bought me three more seasons without burning as much oil, but the engine didn’t have the power it had as a new mower and used more gasoline. The mower just wore out. I decided not to replace the engine because many parts were no longer available. The handle broke and a replacement wasn’t available. I fixed the handle with electrical conduit and hose clamps. The mower had a cast aluminum deck and did not rust out. The product safety commission no longer allows aluminum decks as the deck may shatter if the blade throws a rock against the deck.
Always entertaining, albeit lacking actual facts. 
Did you take the plastic top shroud off (if equipped) and the metal one under that off, exposing the ignition coil and the flywheel? That’s where the grass collects unless the mower has sufficient filtering on the air cooling intake. It shouldn’t be needed more than every 25 hours or so. You can probably clean it with compressed air unless it has gotten really bad. Saying you did it every month makes me wonder since taking all that apart is a big job, unless you used compressed air. Mice like to go up next to the flywheel and make a nest there too.