will this t6 hold up under high heat ? I cut grass several times this summer in a 100 + temp which makes the engine run even hotter. not much choice when it is that hot every day
Try mowing in Florida where 100 degree heat and heat indexes of 105 are almost a weekly thing. Post 9 was out of the manual for your motor. I run Mobil 5000 10w30 in all my mowers engines, Kohler, Kawasaki and Hondas and have never had a problem with any and I run my mowers 6 days a week.
Lawnmower engines were designed to run on regular motor oil as the manufacturer recommends. Synthetic motor oil was designed for automotive use. Running a synthetic in a Lawnmower engine is not cost effective because of the frequency of change. Will this t6 hold up under high heat, yes but if you change your oil the way you should so will the Mobil 5000 or any other oil you want to use.