[V6-12v] C4 100 new owner questions

[Joe - Audi]

The US octane rating is (RON+MON)/2 and is called CLC.

http://chemistry.about.com/cs/howthingswork/a/aa070401a_2.htm

According to some VW manuals, the CLC rating is usually about 4 points
below the RON rating.

http://type2.com/bartnik/octane.htm

So...  95 RON is 91 CLC, and 98 RON is 94 CLC (approximately).

I run 93 CLC in my '94 100 S and get about 21-22 mpg in light city
driving.  I'm sure I can do better but still have some gremlins that I
haven't kicked out of the engine bay yet...

-Joe

James4ihl at aol.com said:
> I don't know much about petrol (gasoline?) in the US - but over here the
> minimum octane rating for that engine is 95 roz/ron. The recommended, and
> what I
> always put in, is 98 roz/ron... so 93 could be a problem, potentially,
> unless
> they radically changed the timing on the US model. if they didn't it
> would, at
> the very least, switch over to the second timing map, which retards the
> ignition by a few degrees...
>