85 Ranger,foam in oil

My buddy got it with some water in the oil but has changed the oil twice since then. He went from 10-30 to 20-50 last time to bring pressure up. Checked the oil and there's foamy bubbles in it. Drained the oil and oil looked normal and fine though. I'm thinling cracked or leaky head but don't know rangers really. BTW it's a V6 5 speed 79 bronco front end and 90 somrthing J ee grand rear end not that that matters!

You may need to flush the entire system. If you suspect cracked block or leaky gasket, you will surely be losing coolant after a time. Further, with your engine running, with caution, relieve pressure and remove the radiator cap. Check the coolant for bubbles. If you see bubbles, then you know that compression is getting into your water jacket.