Bar oil was not always around, single grade oils were once factory recommended as bar lubricant. Used motor oil has been used on chain bars forever, those bars and chains lasted out the useful life expected of them at the time. I clearly rember buying and using SAE 20 by the steel gallon can from Texaco all through the 60`s and a chainbar lasted as long as most saws did. I have worn out more bars using proper bar oil over the years, likely due to increased chain speed.
Pioneerguy600
Pioneerguy600