ler Kohler M20 and Synthetic Motor Oil

[Gravely20G]

My Kohler M20 Owner's Manual shows an Issue Date of 7/85 and Revised Date of 2/94.

The manual says "straight 30-weight oil is preferred" above 32 degrees F and "SAE 10W-30 and 10W-40 are not recommended above 32 degrees F".

Would the issue/revision dates have any impact of why there is no mention about synthetic oil?

 

[exranger06]

FWIW, my Kohler M12 also recommends SAE 30 but I've been using M1 10w-30 since last year and it's been running fantastic. I believe they recommended straight 30 to minimize oil consumption. If it doesn't consume much with a multi-vis oil use it. My engine oddly consumed some oil when I first switched, but after a few weeks it sort of got used to the new oil and stopped consuming oil entirely.