One of the more senior members around here recently pointed out that monograde SAE 30 oils have a HTTS viscosity of 3.7 whereas 10w30 is usually lower. Even the Mobil 1 0w40 I run in the Volvo has only a 3.6 HTTS viscosity. Considering how hot OPE can run, HTHS viscosity is the specification you should focus on.
Why the 30 at spec for lawn mowers?
- Thread starter Sealbilly
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Originally Posted By: Sealbilly
Thanks gentlemen. I read my owners manual for the Toro I just bought and it shows 10w30 but 30 wt for higher temps. Was just curious to why it doesn't call for 10w40 or 15w40.
Air cooled OPE engines use the motor oil as part of their cooling systems and they run VERY hot under high loads in warm weather, hot enough to break down the Vii additives in multi-weight motor oils. In 10w30 for example, Vii is used to keep a lower 10 weight oil thicker when it gets hot so it performs like a 30 weight. When the Vii breaks down completely you are left with 10 weight oil and sludge. As a general rule, the wider the gap between the numbers, the higher the amount of Vii is in the oil. Also, Vii additive has NO lubricating properties of it's own. Modern Vii additives are much better than they used to be, and most synthetic motor oils use less of it, but the Vii will still break down when subjected to very high heat. HD SAE30 motor oil does not have any Vii additive in it so it performs better, protects better, and lasts longer in very high heat applications.
Thanks gentlemen. I read my owners manual for the Toro I just bought and it shows 10w30 but 30 wt for higher temps. Was just curious to why it doesn't call for 10w40 or 15w40.
Air cooled OPE engines use the motor oil as part of their cooling systems and they run VERY hot under high loads in warm weather, hot enough to break down the Vii additives in multi-weight motor oils. In 10w30 for example, Vii is used to keep a lower 10 weight oil thicker when it gets hot so it performs like a 30 weight. When the Vii breaks down completely you are left with 10 weight oil and sludge. As a general rule, the wider the gap between the numbers, the higher the amount of Vii is in the oil. Also, Vii additive has NO lubricating properties of it's own. Modern Vii additives are much better than they used to be, and most synthetic motor oils use less of it, but the Vii will still break down when subjected to very high heat. HD SAE30 motor oil does not have any Vii additive in it so it performs better, protects better, and lasts longer in very high heat applications.
I can relate, for information, my experience with my new to me at the time Gravely walk behind of the sixties vintage. I had changed the oil and filter and used Mobil Clean 5000 10w-40 thinking I was doing the right thing. Its heavier than 10w 30 right? Should be better for summer.... The data plate is missing from this machine. I was running the brush hog implement in temperatures in the mid to upper eighties. Checked the oil at lunch and saw it was low by the check cocks, no dipstick. I topped up with a little penzoil 10w-30. After this I noticed the oil pressure was dangerously low on the gauge. It had been normal when starting cold. I shut down and changed later to Delo 15w-40 HDEO. Oil pressure came right back up and stayed there through any use so far. I later learned about the Gravely recommendation of s 30 wt.
I'll use 5w30 synthetic in my snow blower but summer use simple equipment gets at least 15-40 HDEO.
I'll use 5w30 synthetic in my snow blower but summer use simple equipment gets at least 15-40 HDEO.
I put M1 HM 10w-30 in the 4kW predator generator and the husquvarnia mower which is a 25hp Briggs.
Good stout a3/b3 oil with HTHS 3.5
Good stout a3/b3 oil with HTHS 3.5
I have a tiny little 39cc 500 watt Chinese made inverter generator that calls for 15w40. I haven't got the slightest idea why, but it seems odd for such a little air cooled engine. I'm not sure if it's a clone of something, I can't find any other engines like it.
Originally Posted By: Linctex
Straight 30 can handle some serious abuse.
We had an International 806 diesel go to 15,000 hours with no overhaul
Straight 30 all its life
That's actually not that great for a water cooled diesel...
Originally Posted By: Linctex
Straight 30 can handle some serious abuse.
We had an International 806 diesel go to 15,000 hours with no overhaul
Straight 30 all its life
That's actually not that great for a water cooled diesel...
i run ROTELLA 10W30 T5 blend in my B&S 20HP twin. A very stout diesel rated oil with a HTHS of > 3.5. I see no incentive to run a 30 viscosity PCMO oil in my air cooled engine. Ed
I've run 5w 30 syn and amsoil motorcycle oils. But now i'm running delo 15-40 in push and zero turn.
I stopped using 30 when I tried to pull start a mower at near 32F weather. I forget if I got it to start or not--but after that I decided multigrade might not be so bad after all. I certainly use that in the snowblower for the same reason, although that has an electric start as a backup (or primary I guess).
Originally Posted By: supton
I stopped using 30 when I tried to pull start a mower at near 32F weather.
I run 5w40 in my generator for the same reason. The last time it ran it was for five hours, and it was snowing. Although it is kept in the garage, it could still require pull starting with the engine and oil at 25 degrees F.
I stopped using 30 when I tried to pull start a mower at near 32F weather.
I run 5w40 in my generator for the same reason. The last time it ran it was for five hours, and it was snowing. Although it is kept in the garage, it could still require pull starting with the engine and oil at 25 degrees F.
I currently have PP or PUP (I forget exactly?) 5W-20 in my Honda lawnmower which I added by mistake. I am going to do another change here before the next cutting and replace it with PUP 5W-30, which is actually the recommended oil for this engine/mower.
I run HD 30 since it's recommended. I don't see how my lawn mowers could run any better with anything else. I save my extra 5w30 to top off my car and truck.
Originally Posted By: TheLawnRanger
I run HD 30 since it's recommended. I don't see how my lawn mowers could run any better with anything else. I save my extra 5w30 to top off my car and truck.
Can you use synthetic lawn mower oil? Yes! We have modified our engine oil recommendations to state that you may now use a synthetic 5W30 (100074WEB) or 10W30 oil in all temperature ranges.
I run HD 30 since it's recommended. I don't see how my lawn mowers could run any better with anything else. I save my extra 5w30 to top off my car and truck.
Can you use synthetic lawn mower oil? Yes! We have modified our engine oil recommendations to state that you may now use a synthetic 5W30 (100074WEB) or 10W30 oil in all temperature ranges.
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