More about fuel

[martinglader]

I have a Carrera 3,2 1988 without catalytic converter. In the manual (in German) its clearly stated that only leaded fuel 98 RON (or higher) should be used. I´m therefore using 98 or 99 RON fuel and adding a lead substitute (Shell Millenium 1 ml/l or similar). What do you folks think about that?

 

[graham tompkins]

Martin,
have a look at the archives on this one, which comes up perodically.
General concensus of opinion is that standard unleaded is perfectly fine. I personally use super unleaded, eg Shell optimax or BP ultima simply because they claim to burn cleaner but I have no evidence to substantiate this.
regards

 

[Big_nige]

I used my 3.2 daily for about 3 years doing about 8k p/a. I've tried almost every RON and brand locally available and other than maybe 10-20 miles out of a tank full there is almost no discernible difference, I couldn't pin point whether the extra miles were down to driving style either. I just use BP or Sainsburys as I earn Nectar points from them, I'll occasionally put Super in if its on offer.

 

[Gary C]

I suppose if we were really concerned about the RON to run in our cars, we could fit a knocklink to monitor for detonation during driving.

A knocklink is basically a modern knock sensor connected to indicator lights with a peak hold&indicate circuit. If you get knock (or detonation), they light a row of leds to indicate its severity.

The Subaru boy's are paranoid about them (Some Jap STi's were built to run ~100RON and the ECU could not retard enough to run on 95 in the UK, hence lots of blown up Impreza's

Having said that, seems that noone really has a problem on 95 or we would be reading about it, as someone else pointed out though, compared to the cost of other things, given the low mileage most of us do, why not 98.

 

[nathan 1981 930 G50]

I'm a little sceptical about knock sensors on our old 911 engines. The 964 engines and on were designed to be quieter and may not falsely trigger the detector.

No need to add lead substitute as these cars were mostly built for sale to the US of A and they haven't had lead for years!