Filled 18 hp engine with oil to mow lawn. Replaced plugs before I started. As I was mowing it began to smoke, white or grey I think. After about 1/2 acre it cut off. I checked the oil and it doesn't show on the stick. I put in 30 weight oil and know it was full. It has never done this before. It is an old engine but other than hard starting it is always strong and does a good job.
The model No is 422707.
Any Ideas

Do you have any oil leaks ?
Check the o-ring on the dip stick , check bottom engine seal.
If one of them are bad this will cause the engine to have inside pressure , and will blow oil past the rings , causing it to smoke .
Luck

Thanks DG. I don't see any oil leaking. I cleaned the engine last year and it was dirty greasy at the rear. I haven't seen any oil since. It worries me that I did fill it with oil and mowed maybe 1/2 acre when it shut off. I checked the oil and it doesn't show on the stick. It hasn't done that before. I know it is an old mower but it has always done a good job with plenty of power. It wasn't knocking or anything and I haven't started it since.
Any ideas?

Hi,
The given is that the crankcase oil is getting into the combution chamber and being consumed. How it is getting there is the question.
I would postulate that you have an opposed twin and that it has a bad head gasket. That would push oil up through the breather and into the intake tract. Check it by removing air filter to look for evidence of that oil has made this path. An indication would be oil-soaking of the inner filter. Refilling with oil and running with the filter off may reveal this as well.
Peace,
Clarke