You'll get all kinds of answers. Why? because almost anything will work. Seriously, a small engine will likely run a long, long time on any juice you put in it. Engines that have the correct level and even infrequent changes of oil, will run well for a long life.
My take is as follows:
Best protection: Synthetic with Mobil 1 HM 5w30 and 10w30 as the best. There are a lot of good syns that work fine, if that's your level of cost tolerance. An HDEO syn in the 5w40 is also a fantastic choice.
Fine protection: HDEOs like Rotella or Motorcraft, in either 10w30 or 15w40. You can't go wrong here, strong oils for long life, at a bit less cost.
Completely adequate protection: ST30, or any of the 30wt oils intended for small engines and diesels. These are among the cheapest and protection is super. I like Wolf's Head 30HD. Wolf's head is good oil, $3 a quart and easily available around these parts.
Last edited by bchannell; 05/17/14 11:59 AM.