Small Engines (Lawn Mowers, etc.): Stiga garden mower not moving in gear, oil level, transaxle

Question
Hi Allen

Help! - I get the feeling I have put the wrong oil or too much in in my Stiga garden 12.5hp briggs n stratton ride on lawn mower.
I had added engine oil previous day (oil level didn't look very clear on stick) and spent about an hour cutting grass before engine ceased to drive wheels! Changing gear was difficult but no gears worked and I could push mower up garden in gear without it turning the engine over - has too much oil stopped the clutch from
working? Which oil should I use? How baddly have I upset my mower?
Should I check oil when engine is hot or cold?

Answer
Hi Drew-
Sorry for the delay- vacation-

Verify oil level- if its too high, remove the plug at the base of the engine block and drain some out.  This should not effect the transaxle, so no.... too much oil is not your problem.

I take it your transaxle is a manual?