Some won't agree but you can really. Use a quality 10/30 or 15/40 and all will be well. The recommended grade is a straight 30 which indeed is probably better as air cooled engines run somewhat hotter than liquid cooled but I never use it - and I haven't had any engine problems!
John
April 2009
Not recommended.
Use the right stuff (SAE30 assuming a 4 stroke engine). It's cheap insurance.
Multigrade oils are designed to work within the temperature range of a liquid-cooled engine (90-120 degrees C). Your air-cooled mower engine runs much hotter than that, and the multigrade will be too thin.
EXCEPTION - if you're using a snow-blower at below-freezing temperatures, 0W30 is OK.
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