Dad just gave me his old 20” Poulan farmhand 2900 super clean saw.. about 25 years old still runs. Says on the manufacturers label to combine 8oz oil per gallon gas. He never did. Always put a small 2.6 oz container per gallon. Seems like an awful lot of oil for a gallon of gas. Understand it says that on the label, but is this the normal mix on that saw? If so, how has it run all this time with no issue?