Standard unleaded or Super unleaded

[SteveJT]

I hope someone can help me. I have just purchased a 2 year old 996 Carrera 2 which has the 3.6L engine. Overall I am quite impressed with the car (except for an annoying rattle in the dashboard but I expect to have that fixed under warranty) but I am confused over which fuel to use. The manual implies super unleaded is preferable but the ECU will also adapt to standard unleaded.
Please can someone advise me what fuel I should use.

[turbobloke]

Save money and fill with 95 RON. Save your engine, help the sensors gee up the ECU and save your grin for longer with Optimax 98 RON. Get some Daytona spec racing fuel for a blend and be the cheshire cat, your pockets will also be lighter - - every little helps

[SteveJT]

So now I have three choices instead of two.
Me confused???
Thanks Turbobloke, I will use standard unleaded for day to day use then.

[abarber]

Use super unleaded unless you want to be short-changed a little on performance..

[verysideways]

I found on my last couple of "normal" cars when i used Optimax i got slightly better fuel consumption, so the difference in overall cost per mile was minimal, and i definitely got better throttle response with Optimax.

Just my £0.02

VS

[turbobloke]

Must agree with Alan and VS. I usually use 98 RON.
Wasn't trying to complicate things, honest. The resulting performance difference is more hidden in my case as the ambient temperature makes a bigger difference. I also blend racing fuel with Optimax. But you'll enjoy that great car of yours whatever goes in, it's been designed to cope with liquid 5h1te as available in some foreign climes, so UK 95 RON will do nicely day to day if you go that way.

>> Edited by turbobloke on Thursday 14th October 22:00

[Buster4.2]

I use this stuff in the racer :
www.nitrousformula.co.uk/

It also says it is ok for cats (not the furry variety!)

[turbobloke]

anonymous said:

[redacted]

Try Nutid, now Anglo American Oil Co, on 01929 551557. They supply in drums from, IIRC, 25 or 50 litres up depending on the stock. RON/MON? Well, what spec of fuel do you want?! I usually get Comp 100 or Sunoco GT unleaded at 105 RON (I think) or Comp 110 or Sunoco Supreme leaded at 114 RON. 25 litres of GT fuel is £62 + VAT and delivery, not bargain basement is it?

Using them neat would be like burning money more literally, unless you have a race engine in your road car. Blending works well as modern high performance road engine ECUs will still adjust the ignition advance, turbo boost, etc, and give you more wellington. Note the MON can be lower (GT) so blending is a bit of added insurance but in general you are better off with the racing fuel blend in a tuned / high output engine.

To a good approximation the mixture you get has the average of the RON numbers you used to make it, assuming 50:50, or you can do a weighted average for other ratios. I aim for blends of Optimax and GT giving about 100 RON on a turbo engine with knock sensors as this is a good balance (for me) between improved performance and cost - it's an OK step to my mind if you've already done quite a bit of fettling and want to allow your tuned engine to give you the full benefit from it.

>> Edited by turbobloke on Friday 15th October 15:15

[turbobloke]

Yes in theory OK, but in my example the 114 RON was hard core leaded, so I hope the engine tuning on that car includes a de-cat!

[SteveJT]

Hi Turbobloke, I took your advise and went for the middle option (Optimax) and made a round trip to Cambridge from Surrey today which was nearly 230 miles in total. Anyway, I did not hang about and was in the 3rd lane most of the time and to my amazement I used only just over half a tank and averaged 29.6 mpg. On a good day by driving with a feather touch on the throttle my Noble could only muster 21 mpg.
Will be sticking to Optimax based on this experience. I am saving money

[Andrew Noakes]

The Porsche uses less fuel than the Noble therefore Optimax is better? I don't see how that follows. Do the same journey at the same speed in the same conditions on 95RON unleaded and then you can start to say something about the merits of the fuels.

[turbobloke]

For my part improved mileage is a bonus, having invested a reasonable sum in a few cars and then more in getting them closer to my liking, I'm looking to exploit performance potential more than anything else. There's no need for racing fuels on the road but as there are times when I want the tuning to be fully utilised, I don't mind paying more, and Optimax isn't in that price league...given the generally good things it does to a car's internals I don't mind the premium. Don't think you'll go far wrong sticking to Optimax or its BP equivalent.

[diver944]

turbobloke said:

25 litres of GT fuel is £62 + VAT and delivery, not bargain basement is it?

Hmmmmm, expensive stuff at nearly £3 a litre but to put it in perspective:

My Turbo has a map on the aftermarket chips in the ecu allowing me to use 105 Ron race fuel, which increases the advance and allows boost to increase from 15psi (1bar) to 18psi (1.2bar). This 'could' see my power output increasing from 315bhp to circa 340bhp

Not a huge increase but I would have to spend several hundred pounds to get that much power from a further permanent modification. This way it would just cost me £100 when I wanted to do a trackday that had long straights or wanted to go faster at VMAX