If a person is looking for an engine oil, it's easy to say go buy expensive synthetic oil or manufacturers brand name oil. That's pretty much what's being said by a couple individuals.
Despite the realization that those people are entitled to their opinion, their advice isn't necessarily the best. Anyone can pay big bucks for oil and have a well lubricated engine. All that takes is money. Lots of money relatively speaking.
The objective is to get as good as, if not better lubrication at a fraction of the cost. When a person is asking for engine oil recommendations, they should be given advice that will provide them with the desired lubrication results at a reasonable cost.
HDEO will provide MORE than adequate lubrication. There is NO need for synthetics or expensive manufacturer brand name oils due to relatively short OCIs on ATV engines.
I've used HDEO in air cooled and liquid cooled ATV engines since the early 80s. Never had a problem. The two air cooled ATVs that I have since sold to people I know are still running strong with NO engine work at all. One machine is a 1984 Suzuk 185cc the other is a 1987 Suzuki LTF4WD 250.
The type/kind of oil is of far less significance than regular oil changes. A person is probably going to be more willing to do oil changes using $15.00 per gallon HDEO vs. $10.00 per quart for M/C brand name or high end synthetics.
Proponents from both groups have offered their advice. It's up to the individual to weigh the information and decide which route they choose to take.
In closing, I'd like to say this, the best oil in the world, be it manufacturer's brand name, synthetic or HDEO, will all be rendered useless if mixed with mud and water, which ATVs often see. If you've had an engine stall in deep water, change the oil a.s.a.p. Immediately if you have oil available. Having a gallon of reasonably priced quality HDEO oil on hand is a lot easier to do and more likely to happen than keeping several quarts of expensive oil on stand-by.