Looking after fuel is essential for keeping your engine running smoothly.

Diesel fuel is, like most fuels, a hydrocarbon and mainly derives from crude oil.

We generally call the fuel diesel oil or red diesel (duty not paid), but its proper name is marine gas oil.

The fuel grade burned in our engines is normally to ISO 8217 DMA. You might remember recently there was a lot on the news about petrol changing in the UK from E5 to E10.

This refers to the grade of petrol. Just out of interest E10 has 10% renewable ethanol in it, whereas E5 only has 5% renewable ethanol in it.

Apart from having red dye in it, our marine fuel is very similar to road fuel.

A grade of road fuel is to ISO 8217 DFA, often called white diesel (duty paid); this is used in diesel cars, lorries and buses.

It is a bio diesel, just like the petrol above. Why does this matter?

Well, if DMA and DFA fuels are blended, or if the changes to red diesel duty in the UK for leisure craft demand it, then you could end up with your fuel being DFA grade.

The engine will run just fine on either fuel, but the DFA (biodiesel) can clean out your fuel system because of a higher solvent content, known as organic fatty acids (FAME).

Cleaning out the system sounds good, but the dirt has to go somewhere and it tends to end up in the fuel filters.

The filters will…