Anyone that would suggest running them in the dirt has never taken apart a utility engine used on a cement mixer, tiller, etc. apart. The grit going in with the intake acts just like a sand blaster, literally hitting one side of the port, valve and cylinder and etching it deeply. Putting this in the oil is also counter productive, there are many parts you do not want abraded.
Loose LO206 engines work well but new out of the box show the best.