Every couple years I throw this out. I grew up in a 4th generation tree service. I never saw bar specific oil. All we ever used was the cheapest 10W30 we could get at K Mart. When Dad's business got big enough that we started dealing with companies direct, he would get all kinds of offers to test new products. This was in the early and mid 70's. I remember getting one offer to try a bar oil. Their selling point was the oil was thin and flew off the bar tip faster, carrying heat away with it. They had all kinds of scientific data to prove their product worked. Then we got an other offer and they claimed their oil was thicker and stuck to the bar longer, lubricating better. They had all kinds of scientific data to prove their product worked. We just kept using 10W30, and I have bars that are well over 40 years old, that went through 20+ years of commercial service and then another 20 years of me pounding on them, and show virtually no sign of wear, except no paint left on them. If I'm at TSC and they have oil on sale I might get a couple gallons, same with Ace or Southern States, otherwise I still use the cheapest 10w30 I can find on sale. I think a high flow of oil works best.