well actually the answer is no.
You will not blow the mower up but air cooled engines get a substantilly different addative package to auto oils.
A motorcycle 5-30 would be better than a car oil and mower oilwill be better still.
OTOH if you already keep 5w30 car oil and it makes your life easier then fine.
just remember to change it without fail at the end of every season because the oil will not have the same anti corrosion products as a mower oil.
Any oil is better then no oil and freshe oil is better than old oil.
