I had a small oil leak around my sump, i was using 10w-40w then i change to magnatec, the one with the molicuals that stick to metal to avoid start-up damage, and the difference is awesome, the idle is alot smoother and take off is improved 1000%, stop the leak too.
I fully recommend it.
But generally what Draven says is pretty much the same as i wouldve said.
Hope it works out.
FWIW try a compression check, you never know what condition your rings are in.