Unless I skimmed over it did you ever try a thicker oil like a 20-40 or a straight 30? EDM-s just add to things leaking like mad.

Rememeber the oil we used to run and the relevance of viscosity back in the day. 10w anything is tight stocker oil, not a leaker motor or anything that will rpm.

Remember the good days of straight 30-40-50 weights castrol gtx, thick and green?