Another RON thread..

[naughtyG]

ok so as I was refitting my faux-tank after my clutch M/C escapade, I noticed some stickers on the underside:

and I quote:

Gasoline Specification:

Regular (leaded)
Research Octane : 91 min

Now what do I do - I know this was back in '86, but still.. :ummm::ummm::ummm:

 

[godsend1]

Ya, I saw that on mine a while ago. I still put 87 unleaded in it.
:confused2:

 

[Buster Hymen]

There's a complicated explanation for it that I'll try to find but the octane rating is different than the research octane level so RON 91 is 87 at the pump!:ummm: I know it makes no sense!

Edit

Did a quick search, here is an explanation:

Usually, there are three different octane numbers associated with all petrols. Petrol's Research Octane Number (RON) is measured under simple test conditions. Petrol's Motor Octane Number (MON) is measured under tougher test conditions and at higher engine speed and temperature.

The average of these two values is what becomes related closer to actual driving conditions. This value is known as the Road Octane Number, and is what should be used in filling stations.

Occasionally, some filling stations will confuse these different octane numbers in a bid to embellish on their octane rating claims, and advertise their fuel's Research Octane Number, which is higher than the Road Octane Number. In many European countries, the Research Octane Number is advertised on pumps, so a much higher octane value is common when travelling in certain countries.

 

[naughtyG]

Ok so that makes sense on the RON rating.

But what about leaded/unleaded - I thought that all vehicles sold in the USA since 1973 had to be made to run on unleaded fuel? It's weird then, that on an '86 US model Max, it would recommend leaded gas, no?

Also, AFAIK, the difference between leaded and unleaded engines had to do with the hardness of the cylinder heads and valves. When they eventually dropped leaded fuel in the UK (only a few years ago), vehicles that were fitted with leaded fuel-only motors had to have their heads and valves replaced with 'green' ones (read 'hardened') or use fuel additives to replace the lubricity of the lead. Failure to do so would burn the heads and holes in the valves in the long run..

 

[KJShover]

http://www.vmaxforum.net/showthread.php?t=3187