Synthetic oil in small engines

[Rod in Forfar]

My 2004 Polaris Ranger TM has an 18 hp Robin/Wisconsin industrial engine. Polaris requires 0W40 synthetic in it on a 50-hour service interval. It hasn't used any oil in 500 hours.

The Robin website calls for regular 30 oil in the same engine, warning that multigrades in hot weather will cause excessive oil consumption.

My Bolens/Iseki G174 was using Rotella 5W40 synthetic when I bought it. It seems to work fine, with no consumption after two 150-hour seasons alternating between a finish mower and a bush hog.

Walnut Diary

But a funny thing happened two summers ago. I put synthetic auto oil (I don't remember which one) into the Kohler Commander 18 hp engine on my Simplicity hydro lawn mower. Before I knew it the thing had run out of oil. I couldn't find any on the stick. Amazed, I topped it up with dino until I could get the lawn finished and line up a replacement engine. But the engine didn't seem damaged when I drained the oil later in the day. I put 15/40 Rotella dino into it and it has run ever since without using any oil. I explained to my small engines guy that I might not be needing that engine for a while. He said he's seen that before. Some small engines just burn the synthetic oil up.

 

[TomSeller]

But a funny thing happened two summers ago. I put synthetic auto oil (I don't remember which one) into the Kohler Commander 18 hp engine on my Simplicity hydro lawn mower. Before I knew it the thing had run out of oil. I couldn't find any on the stick. Amazed, I topped it up with dino until I could get the lawn finished and line up a replacement engine. But the engine didn't seem damaged when I drained the oil later in the day. I put 15/40 Rotella dino into it and it has run ever since without using any oil. I explained to my small engines guy that I might not be needing that engine for a while. He said he's seen that before. Some small engines just burn the synthetic oil up.

Synthetic oil molecules are smaller than dino which in part is how they protect better, by getting into places the dino molecules can only think of. As a result, they are consumed faster. Nothing wrong with that but you do need to check your oil more often on some engines, particularly worn ones. I have one car where I went back to straight dino for this reason.

 

[murphy1244]

I use Mobil 1 5w30 in all my gas engines.

 

[Z71]

Aren't most synthetic oils the same?

Nope. Just like any other product you buy they are built for profit at a certain price. Some use cheaper ingredients so they can sell for less. Store brands like Super Tech are oil made to sell cheap because some will think, oh its synthetic so it must be as good as Mobil 1 or AMSOIL and look how cheap it is.

I have used Synthetic lubes since 1975 and never experienced or seen any oil consumption problems in mechanically sound engines. What I have seen though is people using synthetic oil thinking its some magical cure for a worn out engine.

 

[PHILIP8N]

But a funny thing happened two summers ago. I put synthetic auto oil (I don't remember which one) into the Kohler Commander 18 hp engine on my Simplicity hydro lawn mower. Before I knew it the thing had run out of oil. I couldn't find any on the stick. Amazed, I topped it up with dino until I could get the lawn finished and line up a replacement engine. But the engine didn't seem damaged when I drained the oil later in the day. I put 15/40 Rotella dino into it and it has run ever since without using any oil. I explained to my small engines guy that I might not be needing that engine for a while. He said he's seen that before. Some small engines just burn the synthetic oil up.

Personally, I have a hard time believeing synthetic oil was the cause here. What brand of oil, you don't even remember. What weight was it? How many hours was on oil? On what date was initial fill, and what date did it run out of oil? You said it ran out of oil. Was there any oil at all in it? Did you check the oil level before you started? Was there an oil puddle on the ground where it was parked? Was crank case completely drained? My skepticism, I maintain 17 four cycle engines, diesel, gasoline, air cooled, water cooled, small horsepower, high horsepower, and have used synthetic oil since 1993 and never expeienced a problem like yours. I would hate to see someone reading this post and come away that a Kohler 18hp engine cannot use synthetic oil or it will all burn out. Philip.

 

[Gary Fowler]

I began using synthetic starting with my Evinrude 4 stroke boat engine. I put in synthetic and it gained about 200 RPM and ran smoother. I switched from dino to synthetic on my 2007 1500 Z71 truck and also gained about 3 mpg on a 2500 mile trip above what I normally got. I use Shell Rotella T6. So far I haven't noticed any oil consumption when using it.
Helped my brother in law change oil in his 26 HP lawnmower a few days and I will have to see how that goes. We ended up using 3 different brands of oil to fill the crankcase from different partial containers he had but all were 10W40 dino oil.