>About octane:
>I agree that the VW spec of 91 RON is equivalent to 87 octane available
>at a US or Canadian pump. But, the syncro 2.1L engine runs VERY MUCH
>BETTER on 92 to 94 octane.

My father tried on his '90 2.1L both high and low octane gas. He
found, that on high octane the van have higher milage and the
engine have a little bit more power during acceleration.

I guess, the computer shifts the point of ignition forwards on
high octane gas and you will take full advantages of the gas firing.
This is one function of the knock sensor.

In Germany it is cheaper to drive on the expensive high octane
gas than using the low octane because of the higher milage.

Helmut
'80 Camper