If it's oil does it yellow more quickly? Also, I thought oil-based paints needed turps to clean brushes after??
You can buy linseed oil paints in as fine non yellowing quality as you want - it's what artists use traditionally, but the best is pricey.
You don't clean the brushes you suspend them in oil (jam jar, hole in lid, clothes peg) until the next time. It doesn't dry like solvent paints and they stay in good nick for a long time.
Lost of threads about it recently - have a search.