I use the same HDEO oil I use in my semi truck in my Yamaha EF2000is, not nearly the hours on it yet as the OP reference. Schaeffer 10w30 synthetic blend. That oil also gets used in my JD Z445 mower. Not so much because it is a syn blend, but because it has one of the stoutest additive packages I have seen. I don't use the Pennzoil conventional 10w30, but I have seen the numbers on it and it puts a lot of full synthetics to shame on a number of different levels. If I wasn't using the Schaeffer stuff, I would jump on the Pennzoil conventional.
Base oils have progressed so far in the last dozen years, that the differences between conventional and synthetic are not nearly as great, and even crossing over. Actually, all I concern myself with nowadays is the additive package that makes up 20-25% of any motor oil. One can have the greatest full synthetic base oil, but if it has a mediocre add pack, it is will be worse than a conventional with a very strong add pack. There is so much more to oil than whether it is a conventional or synthetic. You need detergents, acid neutralizers, extreme pressure modifiers, friction modifiers, anti oxidation components, anti corrosion components, etc, etc. Unfortunately, the oil companies data sheets are woefully absent of good information on what their oil add pack is. And I know, I know... proprietary information. I rely on Petroleum Quality Institute of America test results in comparing oils. if I have no other way to find out, I buy a quart of what I considering and send in a virgin oil sample to my oil analysis folks. They give me a complete report on the general makeup of the add pack. I have long since left the conventional vs synthetic debate. Those days are gone and a waste of time. I have no brand loyalty and I don't give a rip who is the "official oil" of whatever organization they are paying for that label. Marketing stuff doesn't sway me one bit.
There is only one major area where full synthetic base oils have an edge.... extreme cold weather and truly severe hot temperatures. Both of which most average folks will never experience. But NOACK, or burn off rate, can give one an idea of how well a oil will handle heat. And the Pennzoil conventional I referenced earlier... it has a lower NOACK burn off rate than most of the full synthetics. Equal or better than much of the Amsoil, Mobil 1, etc lineups. Some of us are of the mindset that Shell is using their new natural gas to oil technology and using that base oil for this conventional. They are swimming in GTL base oils over at Shell. The NOACK on the Pennzoil 10w30 conventional is so significantly low, that PQIA did a retest on the stuff to confirm it....
Pennzoil SAE 10W-30 API SN/ILSAC GF-5
I took a Cummins N-14 to 1.4 million miles, doing 30,000 mile oil changes, on a Kendall 15w40 conventional. Only thing I ever had to do to that engine was one fuel injector and an accessory drive seal. Got sold and went right to work for next owner. Synthetics would not have done any better.
