Not familiar with "Bars stop leak". But head gasket issues I have had. I would start by flushing and cleaning the cooling system. Most work can be done in the truck so no real issues just work. Head gaskets fail for a number of reasons. Common ones includes bad cleanup and, failure to clean the threads on the head bolts and the block. A bolt that requires 20 foot pounds of torque to turn in the block will not clamp the gasket properly. A wire wheel on the bolts, and a tap in the block will help. A crack is a issue that can make you weep. But, there are other things that are not so bad. And most are easy and cheap to fix. With a clean cooling system, and for a short time just water in there you can check for oil in the water in little time without spending much money. That is how I would start. Check the oil often for water in the oil. The dip stick is your friend. The oil will get creamy if water gets mixed in it. The level on the dip stick will go up as well. After you know where the water/oil is going you can take other measures. Keep us posted, and others will help as you go. Good luck and I hope you have some fun as you find and fix what is wrong.
