My washer backs up into my half bath sink next door, when water slowly comes up the sink it has tiny air bubbles as well. I tried chemicals, Drain King to no avail, the drain pipe has a metal cross bar so I can't use the snake, any suggestions ?

I assume you mean this cross bar is in the sink drain, right? Open the trap and rod straight into the wall. If its safe to get on your roof rod down the vent stack too. I would first run small amounts of water to flush out the chemicals. I am surprised it isn't backing up into your toilet rather than the sink.