Running in is a very weird science, my MVVS 40 took AGES! but now its one of the best engines i have. if you have a MDS, just fly it right out the box, you'll only half its life with those 3 tanks, any MDS engine thats still running in our club, never got ran in.
i have 2 Magnum 36's one ran 6 tanks though, and treated nice in a fun fly, the other had 1 tank then put on a mini pipe and screamed about in a fast delta, the 6 tanks has no compression and is useless, the other is good as new.
I'm not saying dont run in engines, you have to do sommit, unless its a MDS and then its your own fault for buying it.
Best thing is ask someone whos got one, and treat it gentle for a few runs.
The fuel we're using is Weston UK Liquid Gold, non of that nasty castor stuff in it, i guess that has a diffrence on how ours break in, probably quicker.