Don't know where you are, but 92 octane is the highest available in my part of the country.

AFAIK, a stock '94 351W will run fine on 87 octane.

Despite what many so-called "experts" will tell you, there is no advantage in using higher octane fuels in a low compression engine. Unless you think having a lighter wallet will make your car go faster.

Now, if your engine is modified, you may well need premium fuel. If you aren't sure, fill it with 87 and drive it. Does it ping, especially when going up a hill in high gear? Then try the 89 octane, repeat. Still pings? Okay, you need premium. But if it runs happily on 87, then that's what you should use.

Good luck,
MrFreeze

 

thanks, but your octane-numbers confuse me. I am driving in Norway and here you have the following options: 95 oct. and 98 oct, 98 being the expensive one. Both are without lead. Anyway, I will follow your advice and fill with 95 and listen. Is the "ping" a very easy sound to hear?

 

Anyway, I will follow your advice and fill with 95 and listen. Is the "ping" a very easy sound to hear?

yes the pinging sound is easy to hear, unless you are running open exhausts at full song all the time. it will sound like you put a marble in a tin can and shook it.

 

Gasoline seems to work best, for me. As far as octane is concerned, use the lowest octane you can that doesn't cause "pinging".

 

If it's a stock motor, it won't detonate on 95 unless it's overtimed. I run my somewhat modified 10.2:1 motor on 91 because that's the highest we have.

 

My 1995 truck with the F4TE engine runs fine on the lowest grade unleaded gasoline sold here. The other F4TE I have that I tore down I would guess to around 8.5 to 1 compression. Therefore even though my truck is fuel injected and your car is carbureted I would expect both to be equally happy using the "cheap" fuel.
I once ran across a link that explained how to match up the Euro method of octane rating fuel versus the American method but have no idea where it was. I think it's safe to say the "cheap stuff" is about the same even though we use different numbers.
"Pinging" is a light rattling sort of engine noise. Kind of like loose valve tappets. To test for it you want to find a long hill. Doesn't have to be really steep. Cruise gently up it in the highest gear you can without downshifting. If your car has a pinging problem it will ping on that hill. Once you know what to listen for and with some practice you can make a car ping without using a hill.
If your car pings you might want to play with the ignition timing a bit before giving up on the cheaper fuel. If you change fuel grades, it's OK to have a couple of gallons (liters?) still in the tank when you fill up with the higher rated fuel. An eighth of a tank of lower grade with the rest of the tank won't affect your testing for pinging with different fuel.
By the way, REALLY good English skills. But you still might want to add "Norway" to your location. Like where mine says "SC Foothills USA". You can change it (If you want) in the "User CP" tab up top.

 

RON (Research Octane Number) is used throughout most of Europe. MON (Motor Octane Number) is closer to the real world rating. In North America PON (Pump Octane Number) is the number on the pump. It is calculated by adding RON to MON, and dividing the total by two. (RON+MON)/2.

Check out this link for a more thorough explanation: Fuel ratings, RON, MON or PON?

 

Thanks a lot for fulfilling answers. And to GypsyR: thanks and done

 

I have fond memories of visiting Oslo as a kid. I don't see it ever happening but I'm sure I'd enjoy a return visit. I expect it's a great place to live. I seem to recall it gets dark too darn early though.