The car petrol and diesel thread....

Some thoughts about buying cheap unbranded fuel :

The petrol and diesel that you buy at the pump are not just 'raw' hydrocarbons fuels - they are shipped as that from the oil refineries to local storage terminals like those at Galway docks - where each branded supplier then adds a cocktail of additives, which contain (among others) detergents, anti-corrosives, combustion improvers, lubricity improvers, anti-knock compounds and more.

Each brand (ie Topaz, Shell, Esso, Maxol, Top, etc) has its own cocktail which is a closely guarded secret and which they use in their marketing blurb to claim that their brand of petrol / diesel gives you extra miles per gallon by cleaning your engine, reducing emissions, extending engine life etc. This is probably true to an extent (as the 'drivers right foot' is the main factor in all cars' gas mileage and emissions characteristics ).

However this cocktail of additives is expensive and adds to the overall cost of the fuel - a handy way of reducing the pump cost would be to not add it - partially or completely - to the fuel when the raw base fuel is being formulated and loaded onto the tanker truck at the terminal in Galway docks. This is not illegal as the fuel still meets the legal requirements and standards.

Such fuel is still of genuine source - ie it is not 'washed diesel' or 'stretched petrol', and is of correct octane or cetane rating, but it would be missing some of the key extra components that 'better' fuel will have, the components that help keep the engine running smoothly and cleanly.

Modern cars have their engines controlled by computers via an array of sensors to ensure low emissions and clean burning, if the engine is supplied with a fuel which is missing some of the beneficial components which (for example) inhibit pre-ignition (pinking) or carbon buildup on valves, DPF, etc then it will respond by adjusting the fuel/air mixture, ignition timing or injector timing to try to compensate and keep emissions as low as possible.

This may result in lower engine performance, reduced power, general sluggishness and ironically increased fuel consumption (as you the driver will tend to compensate for all of the above by revving the engine harder through lower gears so that the car 'keeps up').

Hence 'cheap' fuel, though not illegally sourced, may be a false economy.

Long term, it may also result in damage to the engine and exhaust / catalyst system through excessive carbon build-up, lack of upper cylinder lubrication and increased combustion temperatures.

This debate has been raging for years in the UK over 'cheap' supermarket petrol versus more expensive 'branded' petrol....google it and read the articles/forum for yourself

http://www.simplemotoring.co.uk/supermarket-vs-branded-fuels/#.VQFiU3ysV8E

The newer and more complex your car is, the more likely it is to suffer from 'cheap' fuel. Older cars and more simple engines (eg your lawnmower or tractor) will probably be less bothered by the fuel quality.

Does this practice happen in Galway ? I don't know, nor am I suggesting or implying it does at any particular outlet.

All I'm saying is that its worth being aware that all petrol/diesel is not precisely the same and that the cheapest petrol may not always be the best petrol for your car.

Caveat Emptor

Well I think cheaper brands such as Applegreen are grand. It's the unbranded stuff I'd be worried about and I never go near it (2 stations on the Headford Road come to mind).

pleasant Co. wrote: »

So take a punt on a more expensive fuel because maybe that has the right magic formula added to it maybe, but equally it might not but maybe it does...gotchya.

Exactly :-)

But if you buy cheap unbranded stuff and your car runs poorly and you get poor mpg, then it wasn't really cheap either...

<See point 8 in charter, name removed> make my engine jumpy. Not a good sign for the poor old injectors! Avoid