How do you drain the oil in a 250 B&M Blower?
It looks like I have to take the entire blower off and turn it upside down.
That's a stupid design if that is what has to be done.
Also, what type of oil do you put in it?

The design is flawed for sure. What works for me is a hand pump like the one used for gear lube. Flatten the tube a little and extract the old oil through the fill hole.

That Su*ks!
I only have around 45 hours on the blowers.
I think it is time to change the oil, but not sure.
What type of oil?

I use redline shockproof.

If they are like my 420's you want to take off the nose to drain oil and grease the coupler(usually wear out from lack of grease). I use merc spline grease on couplers and merc drive oil in blowers.