Petrol

[TomNauntonMorgan]

98 or 95 RON for the S?

Used 95 for my last car and had to have all four O2 sensors replaced within the year of ownership.

Low mileage in London traffic is apparently why. PCGB Reading have told me that I have to use 98 RON as the car was designed for this. Looks like a lot of extra cash needed to pay for Optimax!!!!


Tom

 

[Michael Downing]

The advice given to me by an OPC (not Reading) for a 996 was that the engine management system detects the type of petrol and controls the engine accordingly. So using RON 95 does no harm, although the accelerator pedal goes a bit further down [] with RON 98 and the fuel economy is a bit better.

However, they mentioned that it's best not to chop & change - if the fuel is a mix of 95 and 98 then the engine doesn't really know which setting to use as either will be non-optimal.

 

[Guest]

Mmm, not sure that's totally true, the car has a knock sensor and as a result, can advance or retard the ignition timing to acommadate any octane fuel without pinking...

 

[TomNauntonMorgan]

The problem is that the O2 sensors get sooted up when the ignition is retarded. So I am told.

Tom

 

[Mark_Bennett]

The car is designed to use 98 (look what it says under the filler cap!)
However it adjusts the timing to accomodate 95. Performance will not be quite so sharp (although who can tell the difference?!)
I use 98 unless forced not to (e.g. When touring in Italy - there is no 98). Why would I want to compromise the performance?

 

[daro911]

ORIGINAL: Mark Bennett

The car is designed to use 98 (look what it says under the filler cap!)
However it adjusts the timing to accomodate 95. Performance will not be quite so sharp (although who can tell the difference?!)

[]Only the stop watch could tell the difference ... If there is no 98 in Italy, and I assume Italian market engines are identical to the rest of Euroland, do they suffer any more mechanical failures and what does it say under an Italian filler cap![&o]

 

[Guest]

I can't tell the difference in performance between 95 RON and 98 RON either but use the 98 as a rule. If only low mileage then additional cost is unlikely to be prohibitive. I reckon for my 10k miles it equates to about £100-£150/year max more running cost. A drop in the ocean compared to the other costs associated with running any car.

Sooting up would be more likely to be caused by the quality of the fuel rather than RON IMO e.g. supermarket fuel vs. shell or BP. Premium brands also have detergent aditives

 

[TomNauntonMorgan]

I used standard Total fuel 95 RON for a year and spent a lot of time messing about having the O2 sensors changed four times!!!

What I need to know is if what I am told by PCGB is true. Does anyone have experience of changing the O2 sensors on a regular basis for a car which only does 14 miles per day?

Tom