ok, I am in a "situation" with my mk1 gti cabriolet (1988).
The engine upon acceleration makes a noise that I was told is "pinking"... basically, the seller had it parked up with half a tank of high-octane fuel in it for about 4 months and then drove it from London to Cambridge, putting in some "normal" unleaded on the way - half way up it started "pinking" (or so he says). Know it's def not the hydraulic tappets, they are fine.
After putting in a bottle of STP Fuel Injector Cleaner and a bottle of STP Octane Booster at the same time straight away, I then topped up the tank with £20 of high-octane unleaded (shell v-power) and drove 300 miles. I topped it up the other day with another £20 of the v-power and added another bottle of STP Octane Boost to that. I have done just over 450 miles since getting the car and putting in the additives and v-power and the noise is still there - it seems worse when the engine is cold.
My main question is... should the noise have got quieter/gone by now?
Onto another question... please forgive me if I sound stooopid
) - when I was buying the STP stuff, I noticed a brand called NOS "racing formula" that says the additive will increase octane in the fuel by up to 6 points - which means that if I added it to the v-power (which is 99) that would make the octane level at 105 (I know that some race fuels are 106) - would this really high level of octane damage the engine if I was to dump in a bottle of this NOS stuff the next time I put a full tank of v-power into the car?
Finally, I have read on another thread that the Inlet/Exhaust & Downpipe Gaskets can have air escape through them, if they have gone, which makes a tap/ticking sound - could it be these gaskets and not the engine pinking?
