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.

[NorCalPR]

87. I ran it that way in my 98 comp and sane way in my 96 brendella. Brother runs a new malibu with a 350, and he runs 87...

Unless its pinging, there is zero reason to run the 91 grade. Octane is there for pinging resistance.


You have to realize these motors were in trucks meant to run on nearly 0 octane...

Run 87 and be done with it. The rest is a waste (unless youre running some high performance motor like a 6.0 or a vette motor)

Sent from my SM-G920V using Tapatalk

[Sdc77]

In France we have 91, 91 +10% Ethanol (call E10) and 93.
I run E10 (91) for 4 years now without issue in the carbed 454.

[Moor]

IMO, you guys should be more concerned about running ethanol free gas in your boats over what octane rating your running. I won't get into the havoc that ethanol will wreak on your fuel system, google can tell you all about that.

If you fill up with 89 or better you shouldn't have any octane related issues. I've used 87 in my old sunsport in a pinch and didn't notice a difference. Modern fuel injected engines with electronic ignitions will retard the timing to prevent engine damage if lower than recommended octane is used. Older boats usually have lower compression engines and were designed to run on lower (89) octane.