It probably depends on the age and the model. I have had an Eager Beaver 1 in use for at least 20-25 years and it has seen lots of use. The manual calls for a 20:1 fuel/oil mix. I have never paid any attention to the oil heavy mix or used any of the super (expensive) oils that come in micro bottles. I have been using any good two stroke oil which comes in quarts or gallons mixed 32:1 in my Lawn Boy mowers, chain saws and weed whip.No problems of any kind.
Dr. B., April 2009
