Unleaded vs Super unleaded

[benmartingolf]

Hi all,

I hopefully pick up the new motor next week and I know the GTI can run on just unleaded but are there any disadvantages to using it or advantages to using super unleaded?

Some people say you can get better fuel economy with the super unleaded but does anyone see any major differences either way?

Thanks, Ben

[barrym381]

if I was buying a new gti it would get the super unleaded as extra cost per tank is minimal 

[benmartingolf]

I think il try to use super unleaded as i think even though you can use unleaded super unleaded is recommended. But I just didn't know if anyone saw any differences.

[monkeyhanger]

if I was buying a new gti it would get the super unleaded as extra cost per tank is minimal 

But it is set up for RON95. It won't be able to benefit from RON98 fuel like the R can. Extra cost per tank minimal? 9% more, for perhaps a slightly better set of detergents and no mpg gains - throwing money away. If the GTI could run appreciably better on RON98 then VW would be recommending it.

Running an R on RON95 will be a false economy though - it will be running more efficiently on RON98, your 10p/L savings buying RON95 will be negated with lower mpg as the car ends up igniting it earlier than it would like to avoid pinking.

Contrary to popular belief, RON98 isn't any more calorific than RON95, it is less volatile so it can be squeezed further  (greater compression ratio, or same compression ratio at a higher operating temp) without pinking before it is intentionally ignited by the spark plug. Running a RON95 optimised car on RON98 fuel just means that the fuel isn't being compressed to its full potential before ignition and at best will ignite in the same way as RON95, at worst you could get an incomplete burn (unlikely, as petrol of both types have a low flash point). The only obvious advantage then is running a tank through for any detergent cleaning benefits.

[2014GTi]

Most modern cars have adaptive ECU's (learning) which monitors the quality of fuel in the tank, after 2 - 3 tank fulls of Super Unleaded you'll notice the difference, it also keeps the engine clean.
I have been using Shell Optimax, V-Power and Nitro since 2000 in various cars and its worth paying the extra few £££'s per tank full in my opinion. 

[mk7gti]

Save the cash. This is from my GTI manual:

[benmartingolf]

Il be taking the manual to bed when I get it. A little bedtime reading. From what I remember its always been an interesting debate.

The difference at the pumps is around 5p per litre i think.

[monkeyhanger]

Il be taking the manual to bed when I get it. A little bedtime reading. From what I remember its always been an interesting debate.

The difference at the pumps is around 5p per litre i think.

Around 10p a litre like for like around me. Shell RON95 = around 114p/L, shell 99 = 124p/L. I can get Esso/Tesco 99 for around 120p/L if I shop around, so that 5 or 6p difference is comparing Esso Supreme 97 to Shell Vpower 99.

[monkeyhanger]

Most modern cars have adaptive ECU's (learning) which monitors the quality of fuel in the tank, after 2 - 3 tank fulls of Super Unleaded you'll notice the difference, it also keeps the engine clean.
I have been using Shell Optimax, V-Power and Nitro since 2000 in various cars and its worth paying the extra few £££'s per tank full in my opinion. 

Cleaner car, for 10p/L? Possibly/likely. Placebo effect? Very likely. A RON 95 optimised car won't advance the timing to take advantage of RON98/99, but a RON98 optimised car will retard the timing to run RON95 without pinking. Smart timing alteration is designed to adapt to the use of lower quality fuel than is desired, due to lack of availability, not to make the car overperform when given a diet of higher RON fuel. In previous years between 2000 and now, VW were optimising certain cars (including the GTI) that sat below the R32 and were optimised for RON98.

At the end of the day it's your money. 

[mcmaddy]

Matt your wasting your time explaining it. Placebo effect will always win over scientific knowledge