My mower doesn't state in the manual how long to warm the engine up for... In fact it doesn't even say to warm it up!
But obviously, me being me, I do.
I usually let it warm up for about 1 minute, but should I warm it up for longer ?
It is a self-propel mower, so I don't want to engage the clutch and put pressure on the engine before it is fully warmed up.
Just like I wouldn't drive a car until it has warmed up a bit.