Car care: Adding the wrong fuel

The best way to avoid putting the wrong fuel in your vehicle is to pause before you grab that nozzle.

NEW ENGINE STANDARDS MAKE MISTAKES AT THE PUMP COSTLY

Motor vehicle engines, both petrol and diesel, have become a lot more refined, fuel efficient and poke out a lot less tail pipe emissions these days.

Fuel quality at the pumps has also improved, which means vehicle distributors can introduce the latest in engine technology without the fear of fuel-related problems and warranty issues.

But engines have become a lot less forgiving these days due to improvements in design and have low tolerance to contaminated or the wrong type of fuel.

With the introduction of Common Rail Diesel engines especially, which operate under extremely high pressures, the days of filling up from the farm tank or an unregulated source are a no-no.

And it's not just diesel engines that are so delicate.

With the fitment of catalytic converters and oxygen sensors to help monitor and control vehicle emission levels, petrol engines have acquired a taste for good quality fuel. As an aside, good quality petrol should not be confused with high or low octane levels.

Manufacturers build petrol engines to accept different octane levels of fuel (eg 91, 95 or 98). In all cases, the different fuels need to be free of contamination to allow engines to operate at their best and to reduce the risk of fuel-related problems.

So if you drive a diesel or petrol vehicle and use a service station that has a reasonably fast turnover of fuel and holding tanks in good condition, then the chances of picking up contaminated fuel is slight.

But what happens when the fuels gets mixed completely and diesel is accidently added to petrol or vice versa?

According to the New Zealand Automobile Association's national manager of road service, John Healy, there were 3419 wrong fuel callouts from October 2012 to October 2013.

Adding petrol into a diesel fuel tank causes serious and expensive damage to the engine.
Because the internals of the newer diesel engine fuel pumps operate on close tolerances and high pressures, they rely on lubrication from the diesel fuel to stop wear and premature failure.

Petrol acts as a solvent, which wipes away any lubrication film between moving parts.
End result is almost instant wear with metal particles left circulating through the entire fuel system.

A repair bill of between $16,000 and $22,000 is common if a modern diesel engine is left to run with petrol in the fuel tank.

But even the slightest amount of petrol in a common rail diesel engine is lethal and the longer the engine is run, the higher the chances are of long-term damage to the vehicle.

The best advice if the wrong fuel is added, whether it is petrol or diesel, is not to start the engine or even turn on the ignition.

In some cases fuel is circulated through the system the moment the ignition is turned on so this should be avoided if possible. More so, if the vehicle is still covered under manufacturer's warranty.

If it happens, contain the damage and completely drain the fuel tank without giving the fuel the chance to circulate around the entire system.

But the best way to avoid it happening in the first place is to do a quick recheck and rethink before you grab that nozzle.

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