What octane fuel do you use?

[zip]

2003 Yamaha 50 four stroke

When at the fuel dock 87. Not sure if they offer a higher octane.

Should I be putting in the 91?
Would it hurt anything to ad 91 to a half full tank of 87?
If I don't need to put in 91, would it benefit me to use the higher octane?

[TIMO]

In the UK its unleaded 93 or 97 ron ,, i was led to believe the 97 ron is contains less lubrication , i used it in my motorbike (gsxr 100 four stroke) a few times , at first it was awesome and seemed to provide more power ,after a few times the bike seemed to lag for some reason so i stopped using it and went back to 93 ron and seemed fine on that, i wouldnt be using 97 in my OB thats for sure .

[Erin]

Pretty certain our local marine fuel is 91 RON. Not sure what my Suzuki handbook says as a minimum to use, but I will take a look later.

[TIMO]

OOps . i was referring to forecourt fuel . dUh `OH

[Poly]

Beware the UK and US standards for measuring/marketing octane are different and so when our American cousins refer to 87 and 91 they are referring to AKI not RON as we do in Europe. "Ordinary" unleaded in the UK is 95 RON, with Super or premium products being 97-98 or in rare cases even higher.

An AKI of 87 is broadly equivalent on 91 RON
An AKI of 91 is broadly equivalent to 95 RON

If it is any help to the OP then 99% of UK outboards are running on 95 RON (AKI 91). A small number of people may be running on even higher fuels (which has been debated here in the past - try searching for Super Unleaded)

[jyasaki]

I run regular unleaded in my F115. 89 octane. No detonation prob's as far as I can tell. FWIW, I think I often get E10 (don't really pay much attention to ethanol), and haven't had problems with it. There are a couple of stations that used to have E20 (as a trial, I think); I avoided those.

jky