Toyota Repair: previa headgasket, engine bearings, combustion chamber

Question
I have a 94 previa sc/le.  It been leaking coolant(from the over flow hose) and over heating.  It spurters sometimes and run rough now.  I check the dip stick and it looks like water or antifreeze in it.  Can I put bar's leaks in to stop a leak if its a headgasket?  Should I drain the oil and change the oil/filter too.

Answer
Doing that won't help, there is too much pressure in the combustion chamber for stop-leaks to work,These cylinder heads also have a tendency to crack, changing the oil and filter will help the engine bearings to last a little longer, water is not a good lubricant and if the problem is not fixed soon the engine bearings may be damaged.