You know, its funny you say that. I noticed that exact effect when running a high dose of MMO in my mower.
I was pretty much testing if MMO even at high levels could hurt performance. Well I ran like 8 oz in a ~32oz tank. The exhaust had a strong odor, I cant even really describe it, it wasnt like a burning smell, an oil smell, idk what to call it. But it immediatly made me feel a bit of nausea come over me. Didnt smoke or anything and ran quite well but it had this odor....
Continued for the whole tank(tank lasts about 45-60mins). I didnt put any MMO in the second tank that same day and the smell was totally gone. If I run the concentration lower it doesnt happen. I dont know if maybe whatever solvents in it arent fully being burned and its making its way out of the exhaust or what.
I will say the mower gets better mileage(if you can call it that). Tank used to last 45-60 mins now its not uncommon for it to last 75 mins. Same conditions, even from the same 2.5gallon container.
