I just like arguing with Mike. He gets all shouty and types his NO’s in all caps.
OK. As long as one of you is in on the joke, then. 
To be clear: I meant there was no mention of a necessity to use synthetic. As you circled in red, they say synthetic may be used if it meets the other criteria.
And the confusion also comes from the fact that the ONLY oils that meet the spec, other than Honda’s oil, are synthetic.
speak for yourself
It’s not confusing for me
in fact, in my opinion it’s very clear cut
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Well, same here, but 106 posts in, some confusion must be out there…
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Carolyn, what is the record for highest number of posts in a thread?
this thread is not even close to that 
Just go to the top of the discussion menu and click on the “replies” button. That will sort it by the reply count.
The highest is 3.9K, then 1.6K, then 763, 624, 506, 442, etc.
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Sure there can be a difference. As stated…0w-20 or 5w-20…the oil is it’s thickest when oil is cold.At colder temps 5w-20 may be too thick to give proper lubrication. And the majority of the US population live in areas that get cold enough to make a difference.
Check the link:
Specifically, I will refer to
Let’s assume, I use 0W20 at it’s rated minimal temperature of -30C, then I will need to find where 5W20 has to be no more viscous than 3250 cP to “meet the manufacturer spec at higher low temperature”.
Somewhere -20C or so, 5W20 will happily do no more than 3250 cP, so from the engine designed characteristics, it will provide the minimum flow recommended, at a higher lowest temperature threshold to compare to 0W20, then they become equivalent. The Amsoil comparison study I quoted above in the thread show that manufacturers routinely have the cold viscosity substantially lower than the maximum required by the spec, BTW.
The higher you go, the more you move out of the zone where lubrication might not be sufficient, but somewhere around -20C is the point from which it IS sufficient by the spec.
I’m not sure what exact threshold constitutes “the majority” for the US population, but here it some quite outdated map view:
For me it looks like quite a lot people would benefit from lesser oil evaporation rates versus the cold start performance they will never need, but it brings back the questions of “different specs for different climate zones”, “summer oil vs. winter oil”.
I will remind that I’m not questioning why Honda requirement is 0W20, as IMHO it is purely about logistics and cost of post-sales support. It is not about the technology.
Thanks very much
Quoting Bob The Oil Buy…That’s funny.
The Northeast Midwest and West account for about 60% of the US population. Benefits of oil in Cold with todays tight engines - seems like more engines can benefit from a thinner oil at startup.
At 114th post in this thread, we are nowhere to get to 1.6K record
I’m not very much interested to get to “one fits all” answer here, as we already know the answer, it is “0W20”
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Tom McCahill answered all the oil questions in his book: “What You Should Know About Cars” published back in the early 1960s.
Here are the important statements:
- Multi-viscosity oil: 10W-30 is a lousy number 10 and a lousy number 30. The only purpose is so service stations do not have to stock as many single viscosity oils. Saves shelf space.
- Detergent oil: “I prefer detergent oil in the bathtub, but not in my crankcase”. Detergent oil holds the carbon particles in suspension and the particles are whipped through the engine bearings with every revolution of the engine.
Tom McCahill went on to state that with his personal cars, he always ran one viscosity above what the manufacturer specified. He claimed that he never had a car that burned oil in less than 80,000 miles.
Back in 1958, Oldsmobile engines had problems with camshafts breaking. Some dealers had significantly more camshaft failures than one would expect. Other dealers did not have problems with camshaft failures. It turned out that certain brands of 10W-30 were causing the problem. Oldsmobile released a statement that 10W-30 was not to be used in Oldsmobile engines. Only straight viscosity was acceptable.
In my 1978 Oldsmobile Cutlass with a 260 cubic inch V-8 engine, the manual specified that either 10W-30 or 10W-40 should be used. I used 10W-40 figuring that the higher the viscosity, the better the protection. However, I kept having the problem with spark knock. Every month I would add a can of Casite Motor Tune-up to a tank of gasoline. I would also pour a a can of Casite Motor Tune-up directly through the carburetor with the engine idling. I would then take the Oldsmobile out on the interstate for a hard run. I switched to 10W-30 after I heard an episode on Cartalk that the polymers in 10W-40 to increase the viscosity range caused the carbon buildup. After switching 10W-30 I had no more carbon buildup and I never had to add any oil between changes in 240,000 miles I drove the car.
Now I don’t advise going back to the single viscosity non-detergent oil. I also think synthetic oil is the way to go. My pushtype lawnmower that I bought in 1992 has a Briggs and Stratton Quantum engine. The manual calls for straight 30 viscosity heavy detergent oil. The engine began burning oil so heavily that I was fogging for mosquitoes as I mowed. I pushed the mower aside and bought a used Black and Decker battery mower from a friend. After one season, I had to replace the batteries. The new batteries that I installed only lasted two seasons. I bought another set of batteries. I mowed for five minutes and the mower quit. Something in the control board failed. Parts aren’t even available. I got out the old gasoline mower and filled the crankcase with 10W-30 full synthetic oil. The full synthetic under the house brand at my local Rural King farm store was $2.79 a quart and the non-synthetic heavy detergent straight 30 weight was $1.79 a quart. I’m cheap, but I decided to gamble the extra dollar. The oil consumption kept decreasing each time I mowed until now I don’t have to add oil. The blue smoke out the exhaust is gone. The Black and Decker battery mower went to Goodwill instead of the gasoline mower that I was going to give Goodwill.
Now I realize that the new battery powered mowers that use a lithium ion battery are far superior to the battery mower I had with its sealed lead acid batteries. However, I’ll continue using my old gasoline mower until it gives out. I may then replace it with a lithium ion battery mower.
My reasoning is that if full synthetic oil extended the life of the my mower that I bought for $250 back in 1992, it’s certainly worth using in my 2017 Sienna van that cost $28,000. I have driven in extremely hot weather with the Sienna loaded in mountain regions with OW-20 in the crankcase and I never had to add oil. I’ll go back to my vacuum tube 12" screen television in place of my flat screen TV before I would go back to non-synthetic oil.
Follow that advice in today’s modern engines and I’d be surprised if the engine last 50k miles. Engines have changed dramatically since the 60’s…ans so has engine oil.
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@MikeInNH I think Tom McCahill’s advice was out of date even in the early 1960s. My dad bought a 1954 Buick from a friend in 1955. I bought the car from my dad in 1963 when I was a graduate student. When I sold the car two years later, it had over 160,000 miles and was still on the street two years later. When the Buick was in out family, the heads and pan had never been off the engine, and it still ran well.and used no oil. We always used 10W-30 heavy detergent oil.
McCahill had some interesting ideas about auto maintenance. Back in his day, there was a reluctance to use detergent and multi-viscosity oil. That reluctance was unfounded. I think today, the reluctance to use synthetic oil has no basis. I use it for everything (I even switched to synthetic rotor oil for my French horn valve bearings).
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I saw that the other day at the music store…I was definitely surprised to say the least. That also reminds me, my horn is overdue for a cleaning too so I’ll probably go pick some up.
Make sure to use manufacturer recommended weight and grade!
@thegreendrag0n
The synthetic rotor oil for horns does come in two different viscosities.
Also, Conn and Holton sell rotor and valve oil with their company names on the bottle.
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