What weight oil do I put in my 20 horse power riding lawn mower ?

I have a sears 21.5 hp rider and sears recommends 30wt. Be sure to check the oil level before each use.

Hope this helps.

Non-Detergent oil. Typically 30 W ND.

It depends on the manufacture. Different engines use different weights. Perhaps I should not say it depends on the mfg, because some mfgs will use different wts. For similar engines. Take Kohler for instance, they use sae 30 AND sae 10w30.

1Mike2,
Different manufactures list different weights for different outdoor temperatures.
I use mostly sae 30 in summer. Use 10w30 or 5 w 30 in winter.
Mike