What you should know about fuel additives and your boat

Old fuel, half-empty tanks, water ingress, diesel bug and algae are just a few of the conditions that can arise from infrequent boat use.

Dirty fuel finding its way into you marine engine can lead to catastrophic failure. At best, your inline fuel filters will be clogged with contaminants.

Of course, that’s the very purpose of a good filtering system. It catches the muck before reaching the engine, you drain the inline filter, perform a visual on what comes out and thereafter hopefully know that your fuel is clean when it gets to the engine.

But to increase the life of your fuel, consider an additive. There are plenty of fuel additives and conditioners out there and it's our experience that they all pretty much work in the same way.

We have for a decade used the Chemtech Diesel Power additive photographed with just about every diesel fill and have found it really does help separate the rubbish from our fuel. We can say this completely independently, too.

So next time you head out, grab a bottle of additive intended for marine use for your diesel or petrol supply. And keep your tank topped up, with the right ratio of additive to fresh fuel, to reduce the air-space that can otherwise create condensation (water) in the tank.

Regularly check your fuel filters, drain them and add new membranes and filter components if they need it. Always carry fuel filter spares. Start your engines and try to run them every few weeks, even if you’re stuck in the berth or on the muffs in the backyard.

The same deal applies to portable outboards, which are perhaps best stored with the fuel run dry out of the carbie and that small inline filter under the cowl. This way you will prevent inline fouling.

But do add some elephant juice or additive in your portable fuel tank as well. And store the outboard upright, not on its side. I've killed at least one portable outboard by lifting it prop up, engine down, eventually resulting in saltwater running back into the combustion chamber.

Do not use any of the Ethanol-blended fuels in marine engines. Stick with high octane, buy your diesel from a marina or on-water service with a good turnover, and try and start your engines every few weeks in winter. There's some fuel for thought.