I have M1 5w30 on hand for my two GM cars, so that's what goes in the Honda mower, the 30 year old Tecumseh mower, and the 40 year old B&S rototiller. Never had a problem with any of them.
Probably why Harley recommends a 15W-40 HDEO if a 20W-50 “motorcycle” oil can’t be found. I run Rotella T5 10W-30 blend or a Euro 0W-30 in all OPE(though that will change in CA soon enough) I touch.Rotella 15W-40 may also a good choice. But to say any 10W-30 is "fine" may not be correct. The HTHS (viscosity at high temp) of 10W-30 oils can fall far short of straight 30. I lost 2 Honda water pump engines due to XW-30 conventional oils. I simply switched to Mobil 1, 15W-50 and the problem was solved.
The issue became clear when I understood that XW-30 oils may not be designed to have adequate viscosity at the operating temperatures of some air cooled engines.
The Briggs manuals recommend straight 30 weight for their older engines, but it is getting harder to find. I have looked at Supertech, Rotella, or even just using 10w-30. What do you use or recommend in this case?
Those sorts of charts have never made a lot of sense to me. Isn't a SAE 30 a SAE 30? As in, all three of those oils will be within the same viscosity range at operating temp? Why is the 10w-30 only rated up to 40F? What's so magical about 40F?I have a CHonda generator I bought recently. The manual says I can use SAE30, 5w-30 full syn, or 10W-30 depending on temp. I broke it in with SAE30 but switched now to 5w-30 full syn. I am rethinking switching back to SAE30 based on cujets post? Thoughts? Its not used much - for emergency purposes. I start it monthly is about all? Unlikely I would ever use it under 40F here in South Carolina.
B&S markets their own SAE30 oil - likely made by Warren - sold at Walmart: https://www.walmart.com/ip/Briggs-Stratton-4-Cycle-48-oz-Small-Engine-Oil-SAE-30W/16778644
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No, an oil with VII cannot be marketed as a monograde unless the SAE labeling requirements are ignored. They would not be legitimate in doing so. However a 30W oil without VII that meets the cranking and pumpability requirements for a 10W winter rated oil can be labeled either way.Beyond that, the SAE viscosity specs are actually separate. For example, there's not a 10w-30 spec, but rather a 10w and a 30 spec. So by definition, the 10w-30 meets the same exact specs that the straight 30 does. Put a different way, the manufacturer of the 10w-30 could literally market that oil as straight 30 if they felt like it, and they'd be completely legitimate in doing so. Same thing with all Xw-30 oils.
No, I'm not.No, an oil with VII cannot be marketed as a monograde unless the SAE labeling requirements are ignored. They would not be legitimate in doing so. However a 30W oil without VII that meets the cranking and pumpability requirements for a 10W winter rated oil can be labeled either way.
In your example above a 10W oil is not a multi-viscosity oil. You’re mixing two different grading systems and conflating them with winter ratings.
You are missing this bit:No, I'm not.
The SAE requirements are viscosity specs- 30 means it has a minimum viscosity at 100C of 9.3 cSt, a maximum viscosity less than 12.5 cSt, and a HSHT value of 2.9 or higher. That's IT. Nothing to do with viscosity improvers, cold weather performance, and so on.
The 10w spec is a separate one that oils labeled as 10w have to meet, and it's mostly measured at low temps.
SAE Viscosity Grades – viscosity table and viscosity chart | Anton Paar Wiki
Find viscosity tables and charts for SAE viscosity grades (viscosity and density values with their source).wiki.anton-paar.com
There is more to SAE J300 labeling requirements than just passing the viscosity tests. And yes it is about VII.No, I'm not.
The SAE requirements are viscosity specs- 30 means it has a minimum viscosity at 100C of 9.3 cSt, a maximum viscosity less than 12.5 cSt, and a HSHT value of 2.9 or higher. That's IT. Nothing to do with viscosity improvers, cold weather performance, and so on.
The 10w spec is a separate one that oils labeled as 10w have to meet, and it's mostly measured at low temps.
SAE Viscosity Grades – viscosity table and viscosity chart | Anton Paar Wiki
Find viscosity tables and charts for SAE viscosity grades (viscosity and density values with their source).wiki.anton-paar.com