Not sure why to block rear wheels.
The oil level should be right at the bottom of the covers, you won't loose much if any.
You'll want to get it warmed up first, leave the load on the 3 point. Raise it up, watch for oil spraying or churning from below. You may have to lower the oil level to see where it is coming from if below.
If coming from above it's the cylinder seals. Some seepage is normal, but not spraying.