Noticed when I removed the air filter that there is a very small amount of engine oil in the bottom of the air cleaner assembly. I removed the hose for the crank case vent and found film of oil inside the hose. When the mower sets for a week or longer I see a small cloud of blue smoke out of the muffler when I start it. I'm guessing the reed valve in the vent is not holding? The mower was new last year and has 160hrs now. It is a model SS3225 with the "Toro" made single cylinder engine. The oil is not over full and was changed at 85 hours. I'm using Mobile One Full Synthetic 10W-30 motor oil. Every time this past summer when I checked the oil it has been right on the full line.
If its just a smear of oil I would not be too worried.
Smoke on start up, that clears almost instantly may be oil or an over-rich/flood of petrol - check that you are going through the correct staring sequence, with throttle/choke settings as per operator manual. Most of my mowers - especially those with the combined throttle/choke, will blow a little smoke on cold start up.
New engines (even modern ones) often take a few hours to "bed in" - oil consumption may be slightly higher at this time & then drop to very little (Note: some oil consumption is normal).
As an "old fogy" I would not be inclined to use a full synthetic multi grade oil, in a brand new engine but rather a straight 30W mineral oil, for at least the first few oil changes - moving to the multigrade after everything had bedded in. Also with any new engine, I would do the first oil change at 1/2 the recommended hours of operation and from then on, as per service schedule.
The vent , allows crank case FUME to escape into the air filter housing.
Now crank case FUME is called that because it contains a lot of oil vapour as a fine mist
If the air filter is soaked where the breather tube goes then you have a problem other wise it is system normal .
Because the cylinder lays flat, any oil that drains out of the head into the cylinder will accumulate and cause the engine to blow some oil smoke on start up
This is more pronounced with multi grade oil
