Not REALLY that different. UK uses RON (Research OCtane Number)
North America uses both RON and Motor OCtane Number - MON- added together and
divided by 2
So, typically ADD 5 points to the US # and you have the RON..
So UK uses 90 and 93 in NA terms
Explains it well
NTL opined in
If you want to run a lower octane fuel retard your timing a bit. So long as
the vehicle doesn't diesel you can most likely tune the timing to not ping
or knock with that octane rating. Pinging and knocking _will_ destroy an
engine. That little ping noise is the gas either burning or exploding
prematurely and pushing down on a cylinder when the cylinder is moving up in
it's bore. Ignoring pinging and knocking is a surefire way to kill your
rings real fast if your lucky, if your not lucky, you will need a total
rebuild when your bearings go south from all that extra pressure in the
I say this from experience. My grandma's '68 302 was in great condition
until she let my uncle use it. He ran it with 87 octane for ~6 years,
ignoring the knocking and pinging. The rings are beat, two cylinders barely
hold any compression, and I believe it has some loose bearings in the bottom
end as it makes a hollow knocking sound mostly at low engine speeds. When I
got it from him I did my best to take care of the car but it wasn't enough,
and it didn't even go a year before the parts weakened from his abuse
finally had enough. He saved maybe $200 on gas, and now it's gonna cost me a
fortune. The moral of the story is that it's a lot cheaper to take care of
your car and do it right. If you want to run a lower octane, try it. But
make the proper adjustments and if it still doesn't like it, don't force it.
You'll save a lot of money in the long run.
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