John Boggiano

I'm interested to see that the GT3 specs only mention running on 98 octane fuel.

Now, while I realise the advantages of this, and the fact that the engine was designed to run out it, it's simply not available everywhere.

Presumably, filling with 95 octane (much more widely available) will hurt only performance, and not the engine? Not that I'm suggesting it long-term, you understand, but sometimes it might be unavoidable for a tankful or so...

mrpc12

We only get 91 Octane in California so I'm sure there is no problem using 95.

John Boggiano

Just out of interest, what does it say in your handbook/manual and inside the fuel flap?

Bill_C4S

Careful....US and UK use different definitions for Gasoline octane ratings.

Research Octane (RON) spec in UK

Anti Knock Index in US = [RON+Motor Octane (MON)]/2

As for using lower octane fuels, within a range, the engine management system should accommodate - does the UK manual not have advice on minimum RON ?

John Boggiano

I think the advice is a bit vague in there, IIRC.

Nordschleife

Don't fill it with 95, only use 98.

95 will increase the incidence of pre-ignition. Do not drive the car hard if using 95, be particularly careful in hot weather.

You are in Cheshire and can't get 98? I can get 100 in deepest Slovakia, let alone Germany.

R+C

John Boggiano

It's when I'm out in the wilds of the Scottish Highlands that I'm thinking about.

normank

Put in Single Malt Scotch.

LERA GT2

I can tell you that in the DR, fuel has less than 90 octanes. One of the great things about PCars is that they run on any fuel!

There is probably some power loss because ecu regulates timming according to fuel specs.

In terms of damage to engine, I think none, because Porsche covers full warranties and even extended warranties sold through the PCar dealer.

This issue is one of the great advantages of PCars against some of the other cars. Italian cars always have a problem with fuel.

lawjdc

You Euro guys are spoiled! We are lucky in the States to even get 91 octane at the pump!

mrpc12

Nordschleife

Driving in the Highlands - check the BP and Shell web sites before going, then you have a few useful 'islands'. Strangely, getting 100 on a regular basis in Britain is harder than it is in Czech Republic/Slovakia/Slovenia/Hungary.

Most of my engine problems have been attributed to 'bad fuel'. I don't know why, but the 'best' fuel seems to come from the pumps closest to the refinery - rather like the beer in the pub next to the brewery.

When refuelling in Scotland look out for the 'dinnae 'fess yersel - its a' the same' effect, believe it or not I've had that problem in Switzerland too.

R+C

dasams

Our CA gasoline is 91 which is the average of its RON and MON (see Bill_C4S post). The difference between the two, called sensitivity, is typically 8 numbers so our fuel might be 95 RON and 87 MON. My fuel door on my Cayenne recommends 91 octane and it also states 95 RON.

John Boggiano

Thank you all very much. I'll be happier about occasionally using 95 without thinking I can't venture out into those areas, now.

Could someone in CA, (or elsewhere with 91 Octane/95 RON) just confirm for me what it actually says on their GT3's fuel flap. I'm curious whether Porsche knowingly lowers the 'requirement' (label-only or engine difference?) for those regions.

Nordschleife

Be very careful about making any assumptions. Frequently the ECU programming is modified for US conditions, not just gas but also heat. This is particularly so on Turbo cars, to the point that if I am taking a tuned turbo to southern Italy, I have the progtram changed before going to cope with the low grade fuel and high ambient temperatures. my tuners do this for me happily, its cheaper than fixing a borked engine/turbo.

R+C