Fuelling my GT

[Primus84]

Except Simon the evidence that has already been presented in this thread actually PROVES you're wrong.

[simonpolly]

The tests were not done on a MK6 GTI ,i agree you probably get a slight increase in bhp(very slight) and maybe one or two more miles to the gallon,but it is not more econmical,if you want to pay 10p a ltr extra for a minor increase in bhp thats fine,but it is costing you more money, otherwise they would never sell any 95ron and VW would tell you to use 98ron.

[Primus84]

Simon, the test proved in two totally different vehicles that there is a marked difference. In addition given the information on FSI engines already provided it is clear that whilst they can be run on 95 and indeed some of the MKV GTIs have a stick that says run on 95 in the filler cap, they run better on 98/99.

In addition the PROOF I spoke of shows an increase of over 10% on the BHP figure!

In addition longer term it has been shown that you are more likely to have issues with the MKV engine if you've used 95.

There's no way I'd consider buying a performance vehicle and sticking 95 in. You're spending all that money on the car, spend a little more for quality fuel.

[simonpolly]

I tried some of the tesco super ul in my mk6 gti and to be honest i could not tell any difference,i was checking the tyre pressures on my 2.0ltr fsi touran today when i looked for the pressure amounts behind the fuel cap i noticed it had 98 in large bold and 95 in brackets,i`ve always used 95 in that.

[Primus84]

So your argument is based on the totally unscientific approach of what you "feel" and you think that's more relevant than the tests linked to previously where they used calibrated equipment and were meticulous in their experiment?

Fair enough, not exactly what I'd call proof though!

[simonpolly]

So your argument is based on the totally unscientific approach of what you "feel" and you think that's more relevant than the tests linked to previously where they used calibrated equipment and were meticulous in their experiment?

Fair enough, not exactly what I'd call proof though!

Nope,thats not what i said all i will say is it can not be more econmical or there would be no need for the cheaper 95 that VW recommend

[GolfTi]

VW recommend a minimum of 95 RON. The mk6 will run just fine on that.

However if you want more bhp and mpg then you should use 98/99 RON.

It's up to you if you think it's worth it or not. To me it is.

[Primus84]

Except Simon, we've seen evidence that there is a significant BHP improvement and in addition given how the FSI engine works, the higher octane fuel will improve economy. Whether improved economy and performance are worth the cost is up to the individual. However why buy a performance car and run it beneath its performance level?

[simonpolly]

i except the slight increases and your opinion,but the slightly better mpg does not out weigh the extra cost at the pump,or like i say there would be no need for 95 ron.

[Primus84]

The combined benefit of more BHP and better economy (no matter how slight) is for the individual to decide, however although you can get by just fine using 95, 98/99 is far better.


Regards FSI owners mainly.

The higher the octane rating of the fuel the longer the FSI engine will run in FSI mode.

You see, when the FSI is running in 'Fuel Stratified Injection' mode it creates a lot of NoX (NoX - Very bad as far as emisions go) due to it being such a lean burn, so it has a NoX Cat which abrorbs the NoX, once its full the Nox probe (fancy lambda probe) senses this and the engine switches back to normal running and can safely clear the NoX out with the other gases through the main Cat so it can switch back into in FSI mode again.

The problem with octane levels is, and this is just an example depending on driving styles.

Out of 100 miles average :-

95RON - 90 miles normal, 10 miles FSI (lots of NoX made in FSI mode)

97+RON - 60 miles normal, 40 miles FSI (some NoX made in FSI mode)

Now regardless of what anyone says this is how the engine is built and as its more efficient in FSI mode VW always recommend the highest octane rating for this reason, they did introduce a 1.4FSI for the uk market that is made to run on 95RON fuel for longer but you want to see the size of the NoX Cat, more like a tanker. lol

And after all that, you will get better miles to the gallon running 97+RON regardless of it being an FSI, its they way they are made these days, the ecu recognises when the fuel mixture combusts and will adjust it accordingly, the cheaper the fuel the more retarded the timing, the more retarded the timing the less power, the less power the more you 'need' to put the foot down.