Dirty fuel is any fuel with contaminants in it. This means that almost all fuel is “dirty”. Around 80% of underground fuel tanks have water in them. Water provides the oxygen source for fungal spores (Cladosporium resinae) to grow and consume their favourite food—the hydrocarbons in fuel. Water from condensation also promotes flash rusting of underground tanks, which flakes off into the fuel, unleashing abrasive particles.
When a road tanker delivers fuel to your local service station, it fills their underground tanks at 800-1000 litres per minute, stirring up the existing debris and agitating the contaminants in the tank, mixing them into the fuel. As a result, you can never be sure what contaminants are in the fuel you buy.
If you buy any amount of fuel any time up to two days after a road tanker has filled a service station’s underground tanks, you run a high risk of the fuel being contaminated.
The immediate danger period after a tanker refill varies depending on ambient temperature and the degree of contamination already in the tank, but it’s usually 2-4 hours in summer and 4-12 hours in winter.
Many consumers are lucky and never fill up in the post-fill danger period. But every time you buy fuel, you have the potential to introduce these unseen contaminants into your fuel system.
Fuel Doctor is the simple, inexpensive answer to this problem, and provides a high level of quality assurance for any amount of fuel you put in your car (or other vehicles and machinery).