Best answer you're gonna get. Dealers are just that, dealers and not necessarily real world operators. Take most of what they tell you with a healthy dose of skepticism.Run enough throttle to do the job at hand, but no more than needed, then when walking to the trailer etc, rev it to full throttle here and there for a few seconds to help clear the ports if you are worried about that sort of thing. Good oil will make that a non issue though. Also, run it fast enough not to lug the engine which, if you lug it, can cause the clutch to slip in thick growth and wear prematurely.
All 3 of my echo srm225 trimmers and PAS systems get oozing goop on amsoil saber at 90:1. The least amount of goop was achieved by using VP walmart 2 cycle oil.Bought case Echo Power Blend on an Echo buy 1 get 1 free promo. After about 3 weeks ports were black and black goop literally oozed out. Dealer said run WOT at least 20 seconds on each use before racking and that basically stopped the build up.
No more Power Blend.