Petrol left in tank

I have a 4.88 Quintrex seabreeze with a 2 stroke 60HP Johnson, I recently was on holiday and went out in the boat every day for 6 days, before I left home I put 50 litres of Premium ULP in the tank, after the 6 days I had just over half a tank left, and it is still in the tank. The motor is oil injected from a tank in the stern, so there is no oil mixed with the fuel in the tank, what i would like to know is how long will the fuel in the tank last if I don't use it for a while? Only having external tanks in the past, I am not sure about under floor tanks.


Thanks guys. Mal.

scano's picture

Posts: 1062

Date Joined: 31/05/07

Probably 6 months

Tue, 2017-03-14 16:25

 I wouldn't be leaving it any longer than that. Even at the 6 month mark, it's going to start to go off a little.

add some stabil fuel stabiliser to it if you are going to leave it for extended periods.








D_d_001's picture

Posts: 1396

Date Joined: 09/03/13

good fuel (bp, Caltex) will

Tue, 2017-03-14 16:28

good fuel (bp, Caltex) will last easy 6 - 9 months, probably 12 months with little detriments if it's sealed well.


Money doesn't buy happiness but it pays for my fishing so ...I may be wrong there.

Jackfrost80's picture

Posts: 4904

Date Joined: 07/05/12

I rang BP and had a chat to

Tue, 2017-03-14 16:41

I rang BP and had a chat to one of their technical guys when I did my knee last May and knew I'd be out of action for a long time and he said during the cooler months it'd be completely fine up to 4 or 5 months and then the octane will start slowly dropping off and that topping the tank up with fresh fuel would be enough to keep it good. I'd suggest you put some fresh fuel in after a few months especially as he pointed out I'd get less condensation with a full tank.


If catching wrasse is cool, consider me Miles Davis