Personally wouldn't worry about it ..
Have previously left a car with a tankful of 91 parked up in a garage for 3+ years while I was living overseas, started 1st try once battery charged and never missed a beat while the old petrol was used up
Same time had 15+ litres of 50:1 2stroke mix in a tote tank on the boat, same deal.
I usually stock up on 91 at discounted rates in 20l Jerry cans for my "new" self mixing 2-stroke on current boat, don't really take much notice of how long the cans have been sitting before using, likely some petrol has been in cans up to two years by now.
Maybe I'm pushing my luck, maybe there's nothing to the "old wives tales" about "old" fuel... Who knows?

I'm using fuel stabiliser, the same stuff they use in the premix cans from the Stihl shop. Never had an issue and fired up without missing a beat after winter.
Can't beat a fresh tap though

Update: chewed half the tank doing a loop around taupo with the partner. Had to do the brakes on the ute Saturday which killed my walking plans in the kawekas.

She run absolutely fine but boy driving a boat around pointlessly gets boring. Did majority of the run sitting at 5000rpm and then the last 45mins at full throttle.

Lovely day out

I think there’s a lot of old wives going on about fuel. A lot of it will depend on type of motor, type of tank, octane etc etc. in two strokes I can see that premix oil could seperate over time, and in metal internal tanks that are half full there’s the risk of water from internal condensation- but personally I have left a boat half full in a shed for over two years due to work reasons and topped it up and ran it for a season without missing a beat. It has a newish yammy foutrstroke on it which has been totally bomb proof. Routine service done a month ago and no issues at all. There’s no way I would be pumping out fuel more than three months old- I be left boats standing for three months or more loads of times over past decade and never had a fuel issue.

Agreed- I think with older boats- esp anything with iron/steel tank- or two strokes it probably pays to be more careful. One thing I would be wary of is running very high octane fuels that contain a significant amount ( ie above 5pc) of ethanol/ methanol. Most engine manufacturers clearly state the combustion tolerances of modern fourstrokes. Merc esp seem to havehad many a nightmare with bio heavy fuels- the US forums are full of tales- same goes for all manufacturers in their high output models. Those that are designated commercial models seem to have more tolerance as they are detuned a bit- or sold in markets where fuel purity can be an issue. Personally I stick to a 91 ( US 89 eqv more or less) which is what all the modern engines are designed for- though every third fill I do 95. Am willing to be corrected here but I think some of the cheaper fuel outlets use bio fuel mixed- and it’s hard to get clear data on how much. The big international cos do too but it seems easier to find out what has ethanol and at what pc.

Done a bit of research on local fuels on the ethanol issue- it’s present in the local co’s 98 octanes and above in at least 10 pc of mix. This is the max pc for modern fourssttokes- older models may have problems with it. This (10pc) is really not great at all for two strokes. Ethanol pulls water from the atmosphere into the fuel mix and fuel like this left standing will not only cause ignition issues but can add to corrosion issues in the cylinder head. Lower octane fuels contain no ethanol in nz by and large- esp 91 but two stroke owners might want to check the specs at their local filling station.

Kandrew wrote: Sometimes I’d be lucky to go fishing every 3 months so older fuel get used.

o/b runs on 95 car runs on 95 so no issue tipping boat fuel in to car,either way has to be brought.

Im just waiting for NPD to get back to re alcohol in their 100+. I have found that Mobil and Gul high octane (98  and 100 oct contain alcohol)

Mc Tool wrote: NPD  have emailed me  and say there is NO alcohol in their 100+ fuel