To use 99RON or not.?

[Pcheaven]

curious.

I just read in Haynes that most models can be run on unleaded - with adjustments - I assume the ignition timing

Will using 99 RON negate the need for adjustments?

As I am using my BX as my daily drive I am being very / perhaps overly cautious

Screenshot 2021-05-03 at 14.03.26.png

[Jaba]

Yes the higher RON needs no adjustment. My GTi runs happily on standard RON without any adjustment because there is no adjustment. We used to reckon that if the engine did not pink on lower octane then there was no need to retard the ignition.
My impression is that BXs run ok on standard fuel but possibly a bit better on 97+. We might have to cope with more than 5% ethanol soon and that could change things.

[xantia_v6]

I would ignore the generic stuff in Haynes, which they copied from one car brand to another. Look first at the fuel requirements for your engine in the original owners handbook. Also be wary of sources (including the original manufacturer) that confuse the need of a certain octane rating with the need for leaded fuel (as for a period only higher octane fuel contained lead in the UK).

[Pcheaven]

Conflicting information makes life difficult. Will probably stick with 99ron as my local station sells this and the remotest possibility of an extra HP or two.

[Tim Leech]

I run my TZI on normal unleaded as its a Catalyst equipped car and has an unleaded head but the GT I run on Super. I do find it runs better

[?????]

If you want to avoid ethanol, Esso super unleaded is ethanol free. It's the last 100% petrol available that I'm aware of.

I use it in my XJS. Although mine is late enough it was designed with ethanol fuel in mind (says so in owners book), I still try to avoid it just in case, who knows if it's had any fuel system changes since it left the factory that might not be up to it.