I'm with Vengie on this one. RON is only a measure of how readily something will (or will not) explode/combust/ignite under pressure. The amount of energy released has little to do with that, that is the "calorific value" of the fuel. 2 fuels can have exactly the same RON number, but if one fuel has gives off 5000 kJ/litre of energy more when burned, you will go further on a tank of the higher calorific stuff get better MPG.

Now where did I put Vengies dissertation again...
 
Would you put a cheaper no name oil in your engine? why put a cheaper no name fuel in your tank? personally my P38DT, a little less torque, not starting from cold as good, a little less mpg, boot it & black smoke from the exhaust? supermarket fuel. Changed to Shell & back to normal. (cheap Whisky, good Whisky, which one would you drink?)
 
Dont forget to fill the tank up to the top first before you weld it up, the higher the RON the better, or methanol :D
 
Sorry to resurrect an ancient thread but would be interested to know your thoughts - on a 4.0 p38 (2001) how important is fuel quality? I ask because our local Shell garage has just closed and the new nearest station is Tesco.... thanks!
 
I would say (i dont have the knowledge though just a guess) that shell etc, is a lot better than supermarket crap, they have the problem with too much additives and water in the fuel,
 
I thought fuel had to comply with set standards, and considering the no of cars running s/market fuels,there wouldnt be time for condensation in the tanks.maybe i,m wrong,but I dont think so. I have worked at most of the larger refineries and I have seen tankers queuing in line to fill up from all the companies
 
Dopey said:
I would say (i dont have the knowledge though just a guess) that shell etc, is a lot better than supermarket crap, they have the problem with too much additives and water in the fuel,
Click to expand...

I think that's right, I was mainly wondering whether on the Rover V8 if it cared about that? I used to have an old ex military V6 outboard that would run on fuel no matter how dodgy, how highly strung is the v8?
 
I fill up my v8 where ever I am when the fuel light comes on and the wife's oil burner runs on svo from the cash n carry for the last 30k miles or so and its the same injection pump and injectors as the p38 oil burner if I had a diesel p38 I would be doing the same
 
Dopey said:
I would say the bigger the engine the higher the ron should be
Click to expand...

RON or octane rating used depends on compression ratio. The higher the compression ratio the higher the octane rating needs to be.
 
The busier the petrol station the less water in the fuel as there is less condensation in the fuel.
The busier the petrol station the less of the lighter elements of the fuel will evaporate.
The raw fuel used buy supermarkets or petrol chains is the same, BUT the additives added by companies such as Shell and BP are better.
The contamination of fuel was back in 2007, and happened in the south east of England only affected petrol only and happened to be all the supermarket's supplier in that region. At other fuel suppliers you may get the petrol chains in the same queue for fuel as the supermarket's.
Modern petrol fuel injection cars will happily run on any legal Ron fuel all those sensors and computers will adjust for it. But some performance engines will, when using a higher RON fuel produce more power.
Diesel fuel between fuel stations is less different unless you pay for premium fuel from shell or BP that may make a difference.
 
TheQ said:
The busier the petrol station the less water in the fuel as there is less condensation in the fuel.
The busier the petrol station the less of the lighter elements of the fuel will evaporate.
The raw fuel used buy supermarkets or petrol chains is the same, BUT the additives added by companies such as Shell and BP are better.
The contamination of fuel was back in 2007, and happened in the south east of England only affected petrol only and happened to be all the supermarket's supplier in that region. At other fuel suppliers you may get the petrol chains in the same queue for fuel as the supermarket's.
Modern petrol fuel injection cars will happily run on any legal Ron fuel all those sensors and computers will adjust for it. But some performance engines will, when using a higher RON fuel produce more power.
Diesel fuel between fuel stations is less different unless you pay for premium fuel from shell or BP that may make a difference.
Click to expand...

Low compression engines will run on any fuel high compression engines won't.
 
I did point out that modern engines will run on lower Ron fuel, which they will, the onboard computers will retard the timing and adjust to compensate of the lower Ron fuel. The high compression engines won't provide the listed performance, But they will run without damage on low Ron fuel.
Old type pre computer controlled engines would also run on low Ron fuel ( badly), but if you did it too often you would rapidly damage the engine.
 
TheQ said:
I did point out that modern engines will run on lower Ron fuel, which they will, the onboard computers will retard the timing and adjust to compensate of the lower Ron fuel. The high compression engines won't provide the listed performance, But they will run without damage on low Ron fuel.
Old type pre computer controlled engines would also run on low Ron fuel ( badly), but if you did it too often you would rapidly damage the engine.
Click to expand...

The knock sensor will pick up detonation and retard the timing but the engine will run badly. High compression engines need high octane fuel.
 
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Fuel specification, controlled under CE and by HM tax collector so the fiel is all the same spec, some fuels do have addatives but they are the special branded products.

Having purchased thousands of litres of fuel from supermarkets I would like to thank them for introducing competition into a previously cartel market and saving us Joe public a lot of cash over the years.

Clearly where a supermarket is present fuel prices are 5 to 8p ltd cheaper.

I am yet to see any issues with the stuff
 
I use Esso and try hard to avoid Supermaket fuel, my engine does run better on Esso fuel and I appear to get a small increase on MPG.

I use an Esso garage which is close to our local Morrison's, so Esso are on pricewatch and the fuel prices are therefore the same per ltr
 
Mine is a higher compression 4.6 & if using supermarket unleaded (Morrissons) I can get pinking under heavy load / throttle when running unleaded. Not so bad with BP / Shell etc..... & no issues with LPG as higher octane.
 
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