Like Steve the engine on my M3W only wet sumps way less than 1/2 a quart after a 6 month winter lay up, I use Amsoil V Twin 20/50. I know people who drain the oil prior to lay up and have a big warning sign on the dash saying "DO NOT START till oil filled".

Bruce
1964 4/4 Series V Comp (Megan)
1994 +8 (Maurice) tis no more
2013 M3W (Olga)