Ric,
Thank God someone else on these forums sees this "controversy" of regular oil versus synthetic oil the same way I do(small engines and/or automotive engines). BTW, I have a 2001 Lincoln LS with a V8 that has 151,000 miles over 12 years that does not use(burn/leak) a DROP of oil every 3,000 miles and a 1995 Chevy Silverado with 230,000 miles that uses(burns/leaks) maybe a 1/2 to 1 pint every 3,000 miles(still pretty good in my book). Neither of these vehicles have seen anything except 10W30 Penzoil since their first oil change. I don't add Slick50 or any other "new-age" products in these engines, but upon the recommendation of my mechanic(because of their mileage) I have started to add Lucas Heavy Duty Oil Treatment once every 12,000 miles to both(this is also a "petroleum-based" product as well). I don't trust synthetics or synthetic blends and never will.
Now for my perspective on small engine(lawn mower) applications:
For my lawn mowers I have NEVER used multi-viscosity which can "lead to oil consumption"(this is explicitly stated in my Kawasaki Commercial engine handbook for my Gravely). I have used "ONLY" SAE 30W Briggs & Stratton engine oil(inexpensive and available at WalMart) in all my "small engine" lawn equipment applications. BTW, my first lawn tractor, a 1993 True Value Lawn Chief with a 16hp Briggs and Stratton Vanguard, was in service for 19 years before the deck fell apart and the engine still ran like brand new and did not use a single drop of oil between seasons. Need I say more?
To further elaborate, if you can "see a difference" with using synthetics that clearly indicates better performance and if your engine manual explicitly states that synthetic is OK(and I would assume it would mention a preferred "viscosity" for synthetics) I don't blame some folks for giving a try(this did not seem to be user Ric's experience). But.......bottom line, my Kawasaki FX691V Owner's Manual does NOT even mention the use of synthetic oil and as I stated earlier it specifically says "Using multi-grade oils(5W20, 10W30 and 10W40) will increase oil consumption. Check oil level more frequently when using them." I have to believe what Kawasaki tells me in regard to their engines, therefore my reasoning for continuing the use of Briggs & Stratton SAE 30W oil. Unless further research on the Kawasaki website or a reply from their Tech Support via a "Contact Us" correspondence changes that, most likely I will take my chances on their recommendations. That's my story and I'm sticking to it!!!