Fuel type? 87, 89, 91 octane?

[Fman]

What is everyone running in there boats? I believe the CAT ETX Indmar is calling for 89, does this really make a difference? I have used 87/89 both and never noticed any difference. I also heard running 91 can do more harm than good if it is calling for 89?

Anyone?

Fuekl is spelled incorrectly, should be fuel....woops.

[michael hunter]

At the price of gas these days I run 87 regular in both my 89 351 and 08 350 cat.

[Skylar18]

Running 89 or 91 depending on where I am on the lake when I need to fill up. Don't notice a difference between the 2.

[riveredge]

Modern EFI engines can adapt to 87, 89, 91, 93, whatever you feed them. There is no doubt an optimum fuel they're designed to run on, but the computer will adapt, so don't worry about it. If you fill up at gas stations, pay the extra couple pennies for the right fuel. On a lake like mine where there are only a few places to fuel up and they all carry 87, well, that's what you get, and your engine will survive just fine.

[KG's Supra24]

89 is what I try to run. If it's between 87 or 91, like on my lake, I go 91.

[natemclain]

The marina where I keep my boat has 91.
Seems to work the same as it did when I was filling up before going to the lake in the past.

Nate

[saltare inverts]

My last boat with 351 pcm didnt like 87 octane. It wanted to ping and knock. When I used good octane booster(much cheaper as mentioned in earlier post) knock was gone. My Saltair now doesnt matter. I do watch were I buy gas. Some place will use very cheap low octane fuel. All Caseys general stores do and alot of mom and pop stores. I try to always use phillips 66 or qt etc.

[Fman]

Thanks for all the feedback, will be sticking with 89 when possible... its only about $4-$5 difference per fill up from the 87.

[KG's Supra24]

Agreed, the difference isnt that much. I'd just fill up at popular places, like mentioned above. Places with alot of turnover where the gas is fresh.

[ScottnAz]

Agree with KG, fresh gas is probably the most important factor no matter which octane is choosen.
Right or wrong, I've been running 89+ as suggested in my manual.