Fuel-high octane vs. low octane

[gcgar]

i've got an older motor, '87 was told by mechanic to run high octane. when i use 87 octane my boat won't hardly run. really sluggish. was told with older models it was recommended to run higher octane

[90skeeter]

i have a 90 merc 175 and was told that lower grade is good enough too run in it ,but i should buy it from the better gas stations and not just go with whoever is cheaper

[Chefdave]

I have a 95 Evinrude 225 Vindicator. All of the professional marine mechanics I have spoken with say high octane is best. I only use Chevron with Techron. From what I have been told, Not only does the H/O burn quicker and cooler but also cleaner.
I always run fuel additive (Ring Free). In the past, I have run lower octane, and had problems, especially carbon buildup. Also from what I have read, The real problem with fuel and outboards these days is RFG gas which is said to corrode rubber fuel lines and parts.
Of course What the heck do I know.
Just my 2 cents
Chefdave

[Danny]

gator,

I've a 2002 Merc 225 opti max. It calls for 89 octane gasoline. I've read that higher octane can shorten the life of the motor. As a result, I run 89. sometimes, if it has been a long while since I refueled, I may add a little higher octane to what is already in my tank.

Good luck,

Danny

[HoosierDon]

I run an Evenrude 150 DIHO and the book calls for unleaded regular. Which I guess would be the low octane you refer to. These new motors are computer controlled and I'm sure the mfg engineers know what is best for them. The hi test fuel not only cost more but very well may burn your valves. I'm not sure it will void a warrenty but thats something you should check out.....


Don