95 or 98..................................

[floordoc]

I have a 2003 C4S and recently read with interest the manuel, the car is designed to take either fuel type can anyone tell me is it damaging to the engine to keep running on 95, or should I on occasions put 98 or is it a complete no no and only 98 will do?

[nbetts]

It will run on all grades of petrol available here in UK. It will perform better on higher octane fuels.

The choice is yours.

[cableguy]

When you wine and dine the wife do you take her to Macdonalds????

Only the best for my Porker... If Shell VMax isn't within drinking distance I resort to Tesco (them who are taking over the country) 99Ron.

C.

[911wise]

The cars are fitted with knock sensors and can tell the difference in the petrol type, and are able to adjust the ignition accordingly.

[hutchingsp]

cableguy said:

When you wine and dine the wife do you take her to Macdonalds????

Likewise does she eat Venison every day? I've not seen too many black and white answers as to whether or not you can do any harm using 95 RON fuel, most answers seem to be along the lines of "Porsche say use 98 so use 98" which is fair enough, but it would be nice to know the technical reasons not to use 95.

[997gt3]

I ran with 95 RON in my C4 for about about a year before i saw in my manual it can use 95/98RON. I started using 98RON as you're supposed to get better performance, but on the UK roads I never noticed much if any difference.

[fieldl]

I tend to use V-Power unless I have to resort to Ultimate.
Have never put 95ron in it.

[nbetts]

hutchingsp said:

I've not seen too many black and white answers as to whether or not you can do any harm using 95 RON fuel, most answers seem to be along the lines of "Porsche say use 98 so use 98" which is fair enough, but it would be nice to know the technical reasons not to use 95.

Porsche do not say use 98 fuel - Infact you will be hard pushed to get 95 in the US.

It is simple, Porsche build cars for a global market and their number 1 customer is the US where they struggle to get high octane fuels at the pump.

Your Porsche will produce more power on a higher octane fuel and there are some merits with using fuels with cleaners built in.

Personally I run the highest Octane fuel I can get hold of but sometimes I cannot get Super.

[Lurking Lawyer]

nbetts said:

Infact you will be hard pushed to get 95 in the US.

But their 95 is different to our 95 - the numbers aren't the same. I think from their memory their "regular unleaded" is 89 and their "super unleaded" is 93.

From very vague recollection, it's because we use Research Octane Numbers (RON) and they use Motor Octane Numbers (MON).

[floordoc]

I must agree Ive put both in mine and I can,t tell the difference.

[9hellheaven]

If your tight put 95 in it...if not put 98 or 99 in it!
It will perform better with higher octane..Think of it as cheap fizz verses champagne. Same end result but more pleasure getting their with the real mcoy..

[Dr JonboyG]

nbetts said:

hutchingsp said:

I've not seen too many black and white answers as to whether or not you can do any harm using 95 RON fuel, most answers seem to be along the lines of "Porsche say use 98 so use 98" which is fair enough, but it would be nice to know the technical reasons not to use 95.

Porsche do not say use 98 fuel - Infact you will be hard pushed to get 95 in the US.

The US uses (RON+MON)/2, and a US 93 is equivalent to 98 RON in the UK.

For high compression engines, a higher octane is needed, and if you use a lesser grade the engine produces more power. But if the engine only needs 95, you won't actually get a boost running 98, you'll just get worse fuel mileage and it'll cost you more.

Edited by Dr JonboyG on Monday 19th February 20:06

[cableguy]

I believe that Optimax/VPower also has additional cleaning benefits another reason why I only put the good stuff in her.

In my previous e39 M5 the difference between standard 95Ron and VPower 98Ron was definately noticable. If your going to buy the best (Porsche), you might as well feed her with quality product...

C.

[997gt3]

cableguy said:

If your going to buy the best (Porsche), you might as well feed her with quality product...
C.

There may be some t**ts and c**ts who drive Porsches but since when did Porsches come with them

[Pickled Piper]

cableguy said:

When you wine and dine the wife do you take her to Macdonalds????

Only the best for my Porker...
C.

That's a bit unkind. Lardy or Tubby are the accepted terms of endearment.
pp

[cableguy]

Pickled Piper said:

cableguy said:

When you wine and dine the wife do you take her to Macdonalds????

Only the best for my Porker...
C.

That's a bit unkind. Lardy or Tubby are the accepted terms of endearment.
pp

She prefer's Porker to Beefy she also prefer's KFC!

C.

[paulio]

Porsche `advise` that it`s only really Turbo`s that need to be run on 98 RON fuel to get the optimum performance, otherwise you can get knocking. The naturally aspirated (I would disagree about the GT3 and Carrera GT though!) are ok to use 95 RON. But basically, what everyone else is saying, use 98 RON when you can, otherwise 95 RON is ok (that is unless you have a Carrera GT, then use NASA grade!)

[Adam B]

but Porsche "recommend" 98 RON - or at least it used to say so in the manual and fuel cap of my old BoxsterS

[thegoose]

Try monitoring how the car performs using, say, 3 tanks of 95 and then 3 tanks of V-Power (99octane in the UK, 100 in Switzerland, other places I don't know) and see a) how the car feels and b) what mpg you get. Tesco Super (not available at all their stores) is also 99.

This will sound an odd comparison, but a friend in Switzerland has a Smart (and a Porshche) which he says runs much better on 100, smoother & quieter and more powerful as well as returning more mpg, thereby off-setting the cost. The same will probably be true for a 911, but the differences less noticeable because there is almost always "ample" power available in road use.

In summary, use the highest you can and it probably won't cost you any more to run the car and it'll be running better.

[sleep envy]

£2.50