ITS NOT A MYTH , you should always crank the engine over when doing oil change.
Give any Subaru specialist a phone and they will tell you the same.
Have heard a few stories concerning the above and wouldnt chance it m8, disconnect the c/shaft sensor and turn it over a few times until the oil light goes out, job done [Y] not worth the risk.
p.s. I use Motul 10/60 [Y]
Marty.