Brim my petrol tank or not?

[MedDreamer]

Next week we are back out to Cala D’Or for what may be our last outings on the boat this year. What is the general view on whether or not I should top up the petrol tank to be left over winter? Should I fill the tank to reduce the chance of condensation contaminating the petrol or should I leave it as empty as I can as the petrol may go stale over winter and mixing the old contents with fresh fuel next Spring would be preferable.

I am planning on taking the boat out of the water over winter so it could be 6 months before the engine is fired up again. When I had the S34 I always topped up with diesel but I’m unsure what is the right thing to do with petrol.

All advice gratefully received

Martyn

 

[rafiki_]

The general feeling is brim diesel tanks, and empty (as far as feasible) petrol tanks. Petrol deteriorates as the “lights” evaporate off over time, reducing the octane rating.

 

[AndieMac]

The general feeling is brim diesel tanks, and empty (as far as feasible) petrol tanks. Petrol deteriorates as the “lights” evaporate off over time, reducing the octane rating.

I agree with Raf.

There are petrol stabilisers available also, to be added when the fuel is fresh, prior to lay-up. I've heard the lower octane petrol is less prone to deterioration over time than the higher or premium versions.

 

[MedDreamer]

Thanks to you both for the replies. Weather is looking pretty good for the weekend so I will try to do my best to empty the tank as much as I can ??

 

[superheat6k]

The general feeling is brim diesel tanks, and empty (as far as feasible) petrol tanks. Petrol deteriorates as the “lights” evaporate off over time, reducing the octane rating.

IMHO no point whatsoever in brimming diesel tanks, just adds weight especially when the boat is ashore on the chocs. Tanks do not breathe deeply enough to create any significant build up of condensation. If only as much effort was expended on applying some waterproof grease to the filler cap threads. For petrol it is likely the engine will next be used in broadly similar weather, so make sure the tank vents are closed if possible and then use whats left early next season with a low only first refill to dilute out the by then only partially stale fuel.

 

[Plum]

IMHO no point whatsoever in brimming diesel tanks, just adds weight especially when the boat is ashore on the chocs. Tanks do not breathe deeply enough to create any significant build up of condensation. If only as much effort was expended on applying some waterproof grease to the filler cap threads. For petrol it is likely the engine will next be used in broadly similar weather, so make sure the tank vents are closed if possible and then use whats left early next season with a low only first refill to dilute out the by then only partially stale fuel.

+1 absolutely agree

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