Here on this forum as on many others engine oil is a topic of intense discussion. What brand, what kind - dino or syn, etc. On my initial 1k mile service I changed to Amsoil full synthetic - 20w50 in the engine. Then at the 5k service and again at the 10k service I sent oil samples for evaluation. The results speak for themselves. As you can see the 5k service was in August and the 10k in October - the hottest period of the year. In fact in mid-October in Texas the air temp reached 104 degrees! My oil temp (yes I have oil temp displayed on my Dakota Digital gauges) never exceeded 215 degrees and my trike is bone stock except for a few 'creature comforts' - nothing done to impact performance or engine temps. I do think other brand oils would have performed well also but I am a firm believer in full synthetic in my TG.