Can you only use super unleaded in the GTI MK5?

[Homer]

Hi all, I have recently bought a GTi and have noticed on the fuel cap it says super unleaded, does this mean I cant use normal unleaded? Sorry if this is a daft question to many of you but in all my other cars it usually says super or normal unleaded. Thanks for any help.

[gazcupra]

You can use any unleaded. It just means for maximum performance use a certain RON

[vRStu]

The recommended specification is normally on a sticker inside the filler flap.

You can use 95Ron but you may get lesser performance.  In general V-Power or Tesco 99 will be the drink of preference.

[Gtiain]

If you want the engine to perform to it's full potential then you should use super unleaded. Using normal petrol can be detrimental to your engine also.  However, I'm sure if your desperate for petrol and the station doesn't sell it then you can put normal in.  

[stealthwolf]

Normal unleaded fuel is 95 RON. The GTI is designed to run on either 98+ or 95RON.

Running on V-power or Tesco momentum 99 is provide the car with its optimum power and mpg. Using 95 RON means the car has to retard the timing and hence rediluce the power and mileage. Not buly a huge margin but some people have noticed it.

It's best for the vehicle to stick to 98+RON.

[edd666999]

when standard i used 95RON and made standard power.

only once modified did i start with 99ron

[alexperkins]

Also makes a difference to emissions. Lower RON causes the FSI unit to change settings therefore reducing power, and actually increasing NOX output according to the VW spec sheet!

[ub7rm]

Using 95 will not harm your engine but here is why you should use it in a FSI engine:

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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.

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Credit to 'maxamus' of the golfgti.co.uk forum for the above.

Personally I have tried 95 and have noticed that the performance suffers with 95 - especially at the top end of the rev range.  MPG wise I have not noticed any significant difference but thats probably because my commute doesn't lend itself to the engine being able to go into FSI mode anyway (lots of stop start and variation in throttle) whereas someone cruising up and down a motorway is likely to notice a bigger difference.

I have stuck with 99 though as I like the extra power 

Fuel prices going the way they are going makes you think twice though....

[Madlil]

Great explanation ub7rm.

I find the best solution is to find a local Tesco with Momentum 99 and religiously fill up there. Pricies are set to go up more though - I am amazed that there haven't been further protests......

[Richn83]

No offence UB7RM but I dont agree with the explanation that maxamus has written there.  anti-knock that kicks in when lower RON fuel is put into the angine is to do with the burn rate of the fuel and if the piston is moving in time with the burn front of the fuel.  

If the engine is knocking then the fuel isn't burning uniformly and you will get several burns during a single piston cycle.  engines have suffered from knock well before FSI came along.  FSI is the way that the fuel is injected into the cylinder and apart from timing and volume at different engine speeds that doesnt change dependant upon the fuel quality.

I'm not saying that NO_x isn't formed in the cyclinders with the combustion of fuel and air because it is and the cat is responsible for scrubbing the emissions to remove harmful chemicals.  However the engine will run in FSI mode at all times and will simply retard timing and change AFR (air to Fuel Ratio) dependant upon the fuel in the tank.

He is right that the less power then the more your foot will need to go down for the same level of acceleration.

OP as mentioned above you can run the GTI on 95 or 98, my fuel cap says 98 ₍₉₅₎ you will maybe lose some power and get slightly less mpg, I run my car on 98 as I dont use it on a regular basis, my dad had an A4 2.0TFSI that he only ever ran on 95 for its whole life without issue, choice is yours.

[Kalpsn2000]

My 2.5 months worth of experience

I've had my GTI for just over 2 months now and for me it’s really an evening/weekend car as I take the train to work.

Since picking it up I have actually put in 3 different fuels.

On pickup I put 30L of 95RON (to make sure I got home), second fill up 50L of 97RON (Sainsbury’s Super) and the last 2 fills, 30L each (to keep weight down and also the petrol 'fresher'), I have used 99RON (V Power). The increase in RON is down to reading up on forums

The car was fine on all of them but I have noticed the throttle response is quicker with v power . And as I don’t use the car that much I will be filling up with 99RON from now on (what’s a couple of quid extra every couple of weeks ).

[Bigjimknickers]

Some great info here!
I didn't even give it much thought, then I noticed the 97 Ron notice on the fuel cap!
I quickly stopped at £10 & figured I'd search first before a major fill up, now I'm glad I did as I'll be going to shell V now.

[GTIEagles]

I have only ever used Tesco 99 Momentum on mine (nearest Shell garage is 30 miles away) I briefly had to use BP Ultimate 97 and even on that I noticed a slight loss of performance. These cars are optimised to run on 98RON so anything less and you will get a loss of performance, plus higher octane fuels tend to have additional cleaning detergents which help keep your injectors and valves clean. I would personally pay the extra few quid a tank for the benefits alone.

[Paradox1]

I used Vpower on my stage 2 1.8T as it was mapped on that fuel.

Got a new car now, standard form but I still use Vpower or any performance fuel anyway.

Meth injection here I come

[Bigjimknickers]

Put £25 in last night, (v power nitro) I'll use that up then do a proper  fill up with V power, my missus want to use BP for her nectar card, what's there fuel like?