From the crazy experience I went thru, chasing a darn fouled plug...you'd think i'd go synthetic. When i got this boat, i went thru everything..carbs, raves..etc..boat ran awesome, then tat 1 trip out, wham...fouled port mag plug, installed anutha..fouled it after a few minutes of WOT...so chase'n this darn thing...rv cavity pressure hold, rip'n carbs off umting times..etc,..for life of me, figure it out, until i thought, ahh, what th heck, look at raves, and wtf you know...darn rave was so stuck, had to pry the b**** out with big o flathead.....now, boat loves me again.....but prior to find'n it, yeah, dumped a gal of mineral, when i should've used synthetic, and for the few outings while fouling plug, if kept it at 6-6500rpm..no problems, but I new I wanted it to be right...starboard never a problem...?