pinking??: metallic ticking under load..

[robwill2 at wxs.nl]

Hi,

Since some days I notice a metallic 'ticking' noise (about 
as tiny christmas tree bells, when speeding up from a low 
speed in a relatively high gear (Audi 100, 1982, 132 hp, 5-
cyl, manual)..
My fuel is 98 ROZ (98 degrees octane), but for some time 
now from the same fuel station...
The noise wasn't present before: could it be pinking 
because the fuel isn't real 98 octane??

tx,
robert
robwill2 at wxs.nl