Burning oil

[blade11]

I have a Toro Zmaster with a 23 HP Kohler. It is burning oil and I am trying to figure out why. I have 90 for compression on one side and 150 on the other. The side with 90 is the one which has been causing some problems. The spark plug on this side also gets gummed up real bad. Here are some problems that are related & I have done the following but it continues to burn more oil than is normal: muffler went bad---replaced; replaced head; replaced valves, valve cover gasket; replaced valve seals. Any thoughts or ideas? Thanks in advance

[dgfitz]

Sounds like a bad piston ring, may not look broken when you first look at
it, or a very small crack in the piston itself, very rare.

[mowerknower]

Burning oil is usually head gasket, breather or rings. Do a leak down test and you will find you problem.