Is it true that cheaper petrol from small brand petrol stations you've never heard of is of poorer quality -

Question

- than petrol from stations like shell or bp?

Answer 1

Not in  the US.  They get their fuel at the same depots as Shell and BP.  I used to work for BP and have seen it at the depot.  

The most important thing about deciding where you purchase your fuel is that they be a busy location.  This assures an equally low % of moisture in the fuel.  Because of temperature differentials there is always moisture content.

Answer 2

Not quite.

The actual fuel is the same because it comes from a single refionery. The difference is in the additives.

For example, when it gets too cold, diesel seperates into jelly and a liquid, which still stay seperate as its temperature rises. To overcome this, the wholesaler (Shell, BP, etc,) add chemicals to reduce the temperature at which this waxing process starts.  Cheaper brands may wax at a higher temperature than the more expensive brands.

Other additives are used to help lubricate the engine, reduce carbon build-up, etc.

(For example, there is some research evidence that suggests that continual use of Shell diesel increases the life of a diesel engine.)

Answer 3

In most cases.

Answer 4

Gara, if you've worked in gasoline, then you know that the depots also store the additive packages that are injected during the loading process.  While it is true that base gasoline is essentially the same and retailers load at each other's racks, the additive makes all the difference.

The federal government has minimum standards for detergency in gasoline.  This minimum standard will not keep your engine clean and running at peak efficiency.  Brand name retailers spend millions developing the additive packages for their products, while discount brands purchase a generic additive package.

Several auto manufacturers got together a few years ago and formed the Top Tier standards for fuels.  These standards were developed to ensure that the manufacturers' cars maintained their high efficiency over the life of the engine.  Some of the  makers involved are Audi, Toyota, Honda and BMW.  

In order to attain Top Tier ranking for their fuels, all grades must meet the standards, not just premium.  Using these fuels ensures you're getting a high quality product that will not harm your engine's components and build up residue that robs performance.  I work for a Top Tier retailer, but it doesn't matter which one.  All of them will work for your engine, so pick the easiest and cheapest one to find.

The 2 or 3 cents a gallon you save comes out to 60 cents on a 20 gallon fillup.  If you fill up twice a week, that amounts to less than $75 you save buying cheap gasoline.  Considering you spent thousands buying your car, doesn't it make sense to spend less than $100 a year keeping the internal engine parts clean?