Viscosity and hours between oil changes in small air cooled engines.

Joined
Mar 29, 2010
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Minneapolis
I was around hundreds of pieces of small air cooled ope when I worked in parks. The only time any engine had a problem was when it got north of 15,000 hours (!) or it just ran out of oil because no one checked the level. The only pattern of small engine failure I saw was with tennis court blowers with various 8 hp engines. They consumed a lot of oil since they’d always run at 100%, but they still last 20 years.
 
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Dec 14, 2015
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Kansas
In my experience don't overthink it!! Mobil1 0w30 if running at 20 Fahrenheit or below. The engine will pull start and run right off the bat. This weight is good up to 80 degrees ambient temps. 15w40 dino or 10w40 Mobil 1, 15w50 Mobil1 above 80 degrees for that. Look at my posts, I ran air cooled commercial mowers on a daily basis for many years. Never lost an engine due to the wrong oil weight. Most important is check the oil before you start it for the day. Top it off if it is even a bit low. Main thing is to keep the air filter clean, feed good quality fuel, toss in fuel stabilizer, keep a spare spark plug handy and have a quantity of oil in reserve. That is a win -win situation!!
 
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May 19, 2022
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Michigan
In Houston I would run either 10W-30, 30W, or if the engine is older and looser 15W-40. Those Honda's with the aluminum cylinder will like the heavier viscosity after the bore has worn some.

Synthetic is a waste of money for small air cooled engines that have frequent oil change intervals, especially on a disposable aluminum bore engine. What you want is an oil with a high ZDDP content for protection of areas with thin oil films and against moisture. I recommened Shell Rotella T4. Cheap and easy to find.

Daily oil changes are insanity and abusive to the environment. Such an oil change regimen will not extend the engine's life beyond what it would be if the recommended intervals are followed. Furthermore, with the money wasted on daily synthetic oil changes you could buy a new Honda engine in a few years, a GX one with an iron sleeve and crank bearings. I bought a used Honda GX for my mower 15 years ago and after yearly conventional oil changes it still runs like new today. I measured compression this spring and it's the same as when I bought it. The rest of the mower is falling apart but that Honda GX is indestructable.
 

z71bill

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Sep 26, 2021
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In Houston I would run either 10W-30, 30W, or if the engine is older and looser 15W-40. Those Honda's with the aluminum cylinder will like the heavier viscosity after the bore has worn some.

Synthetic is a waste of money for small air cooled engines that have frequent oil change intervals, especially on a disposable aluminum bore engine. What you want is an oil with a high ZDDP content for protection of areas with thin oil films and against moisture. I recommened Shell Rotella T4. Cheap and easy to find.

Daily oil changes are insanity and abusive to the environment. Such an oil change regimen will not extend the engine's life beyond what it would be if the recommended intervals are followed. Furthermore, with the money wasted on daily synthetic oil changes you could buy a new Honda engine in a few years, a GX one with an iron sleeve and crank bearings. I bought a used Honda GX for my mower 15 years ago and after yearly conventional oil changes it still runs like new today. I measured compression this spring and it's the same as when I bought it. The rest of the mower is falling apart but that Honda GX is indestructable.

Honda owners manual recommends oil changes after 25 hours when used under heavy load or in high outside air temperatures. One a day is not insanity it is the manufacturers recommendation. I recycle the old oil and it only uses 12 ounces - abusive to the environment are you joking?

Hot as hell Houston after a hurricane is the intended use of my generator - so changing it everyday is what the manufacturer recommends.

It is hard to even find conventional 10w30 - Walmart doesn't even carry it in the store.

I can buy a 6 quart box of 10W30 Havoline (Chevron) for $19.98, synthetic blend is $19.98 and full synthetic is also $19.98.

Back a few years ago conventional oil was cheaper - not so much anymore -

If the price was the same - which it is with Havoline would you still use conventional oil? Why?

I have a supply of 30 weight, 5w40, 15w40 a bunch of 5w30 that I use in my truck and some 10w30 -56 quarts on hand - it will be a game time decision.

If cold then 5W30 or 10w30
If hot then straight 30
If really hot than 15w40
 
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May 19, 2022
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Michigan
My Honda GCs all use 20 oz. 50 hour oil change intervals. Must be different in TX, here in MI the synthetic is significantly more expensive then conventional.

Looks like I was wrong about the OCI. If 25 hr intervals are what your manual says then do it.
 

z71bill

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Sep 26, 2021
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My Honda GCs all use 20 oz. 50 hour oil change intervals. Must be different in TX, here in MI the synthetic is significantly more expensive then conventional.

Looks like I was wrong about the OCI. If 25 hr intervals are what your manual says then do it.

I order oil from Walmart online - over $35 free shipping.

I just ordered some

Valvoline Premium Blue Synthetic Blend 10W-30 Heavy Duty Diesel Engine Oil 1 GA from WM - $19.31​


I was low on 10W30 and this should be top notch stuff - regular price was $28.47. I am a cheap skate I like stuff on sale!

My Honda requires 50 hours or 6 months between changes for normal operation - run it a few hours here and there I guess - but requires more frequent service = every 25 when temps are hot and hard use - I think running it 24 hours straight only stopping to put gas in it is considered hard use. Look in the fine print I bet your Honda does too.

The way I look at it is even using higher cost oil it is less than $2 to change it - the 15W40 Chevron I bought on clearance it would only be $1.20 to change the oil.

If I run it a week straight that would be around $10 for oil - the gas I will use over 7 days will cost me $120. $10 doesn't seem like much.
 
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With the Hondas I’ve found more issues with sensitivity to dusty fueling conditions. Every one I’ve had eventually develops a surging throttle condition, including my fairly new eu2000i. And in every case, cleaning the jet and installing a fuel filter makes the problem go away.

in the eu2000, there’s not much room for a filter, and the gas line is like 1/8”. I used a metal r/c filter designed for gas in it, and sealed its threads with seal-all as an extra precaution. Of course, when I did this, I also had to clean the jet because refueling on a dusty day is all it took.

with a heavily used mower, M1 5-30 was too thin when mulching in the southern heat here, and the engine was damaged over time. 10-30 solved the problem and the sparklies stopped showing up in the oil. It kept increasing start up smoke and consumption until I changed to 10-30 and it remained the same, but didn’t get worse, after that. Based on that, I won’t get thinner than a 10-30 in ope.

oh, and I’ve run that eu2000i nonstop for days following storms. Using synthetic oil, a week is fine as long as you check it.
 

z71bill

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Sep 26, 2021
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With the Hondas I’ve found more issues with sensitivity to dusty fueling conditions. Every one I’ve had eventually develops a surging throttle condition, including my fairly new eu2000i. And in every case, cleaning the jet and installing a fuel filter makes the problem go away.

in the eu2000, there’s not much room for a filter, and the gas line is like 1/8”. I used a metal r/c filter designed for gas in it, and sealed its threads with seal-all as an extra precaution. Of course, when I did this, I also had to clean the jet because refueling on a dusty day is all it took.

with a heavily used mower, M1 5-30 was too thin when mulching in the southern heat here, and the engine was damaged over time. 10-30 solved the problem and the sparklies stopped showing up in the oil. It kept increasing start up smoke and consumption until I changed to 10-30 and it remained the same, but didn’t get worse, after that. Based on that, I won’t get thinner than a 10-30 in ope.

oh, and I’ve run that eu2000i nonstop for days following storms. Using synthetic oil, a week is fine as long as you check it.

Not all Honda engines use the same oil change maintenance schedule!

Your eu2000 is 100 hours or 6 months...

My EG2800i is 50 hours of 6 months under "normal" operation and 25 hours or 3 months under high outside temps or continuous / heavy use

But IMHO it is foolish to run your eu200i nonstop for a week without changing the oil. 168 hours is way over what Honda recommends.

It takes .42 of a quart so I will guess about $2 to change the oil.

Are you really that lazy and cheap?

I know changing the oil in the eu2000i is a little harder than some units - I have a similar 2000 watt unit and you have to pick it up and pour the oil out of the fill hole - but even the first time I did it it only took a few minutes.

The thing is - not changing the oil in your eu2000i will most likely not cause a total failure - it just reduces the life.

So do proper maintenance and it will last for decades of occasional use abuse it and it will start smoking, fouling plugs and lose output.

Your unit your choice - but I take a totally different approach to maintenance.

Many OPE manufacturers now recommend 5w30 - and since both 5w30 and 10w30 are 30 weight when hot it really only matters at start up.

The reason your mower was starting to smoke wasn't because you used 5w30 - it was because you didn't change the oil often enough. Oil gets contaminated and it causes excess wear on the rings - worn out rings from poor maintenance can be helped by using a heavier weight oil - but the damage is already done - using a heavier oil just helps cover up the problem.
 
Joined
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I wouldn't either if my plan was to run it for 100 hours straight. But does changing it every day change the view?

While researching oil a while back I discovered that 5W30 has a higher viscosity at 100C than 10W30 -

Mobile1 5W30 Kinematic Viscosity @ 100 C, mm2/s, ASTM D445 = 11.1

Mobile1 10W30 Kinematic Viscosity @ 100 C, mm2/s, ASTM D445 = 10.4

High mileage M1 5W30 Kinematic Viscosity @ 100 C, mm2/s, ASTM D445 = 11.9 the 10W30 = 12.

I was thinking the 5W30 is an OK choice because it maintains a slightly higher viscosity at 100 C I am sort of pulling that out of my butt with no real scientific reason. I don't know much about HTHS and how it relates to viscosity at high temps -

I read some stuff about HTHS a while back - a lower number means it flows easier at extremely high temps - which gives you better fuel economy.

So 5W30 has a higher viscosity at 100 c VS 10W30

But 10W30 has a higher HTHS at 150 C VS 5W30

So does this mean running at high temps of 150 C the 5W30 would break down faster?

Do I care if I am changing the oil everyday? Right back where I started.

Does it really matter if one oil is 11.1 and the other is 10.4 at Kinematic Viscosity @ 100 C, or of one oil is 3.7 HTHS and the other is 3.5?

These differences seem small - when compared to something like a 0W20 with a Kinematic Viscosity @ 100 C, of 8.6 - IDN what the HTHS is but I will assume much lower than 3.7.

Deep stuff this oil anal
The 5W-30s higher viscosity is from more Viscosity improvers additives . Under heat and load the oil with more viscosity improvers is thinner between the parts, if we want to over think. Clean fresh oil is happy oil and what is the recommended oil change interval in the manual and is there an oil filter?
 

z71bill

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Sep 26, 2021
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The 5W-30s higher viscosity is from more Viscosity improvers additives . Under heat and load the oil with more viscosity improvers is thinner between the parts, if we want to over think. Clean fresh oil is happy oil and what is the recommended oil change interval in the manual and is there an oil filter?
no filter - I totally agree with your fresh oil is happy oil.
 
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