High Octane query

[Dutchone]

A question for the Fuel Guru's.
I use 97+ (Optimax or similar) in my Griff and I read on a PH thread that high octane fuels tend to loose their octane content quicker than their slightly lower octane counter parts i.e. 95.
If this is true and my question is based on not having to use the car very much through the winter - is it worth filling the tank with 98+ and then leaving it to reduce to around 95 (or lower) rather than putting 95 in the tank in the first place.

I know there will be a contingent of owners on here who use their car all year round, and will be of the opinion that this fuel question need not be asked if the car is driven regularly.
I, like a few other owners choose not to use the car very much through the winter(other than to give it an occasional blast on dry unsalted roads), and the same fuel could be in the tank for two months or more.

Paul.

[snorky]

over time RVP ( Reid Vapour Pressure ) might deteriorate, but as it's bloody cold over winter shouldn't cause much problems...

[griffter]

My approach (two lay-ups of up to 6 months) has always been to fill the tank before laying up (IMHO letting the system dry out could be problematic). That way less volatile fractions of fuel are going to escape, relative to all of the fuel in the tank. I'd have thought super rather than ordinary would be beneficial for the reasons you propose. A bottle of octane booster to make up for any such loss before the first run out, and the car's always started first time. Just make sure you're happy with the car sitting around with a full tank of fuel - ie no fuel leaks, and no sources of ignition.

>> Edited by griffter on Monday 19th December 16:15

[GreenV8S]

Leave the tank brimmed, that way you don't have any condensation problems in the tank during the lay-up.

[Nuggs]

Sorry, I was clearly talking bs, I'll delete my original post