Leaded/Unleaded Fuel

Paul Glasson · Paul Glasson's Garage

Hi,
This is the first thread I have started so lets see how it goes.
I have had my 84, 944 for about 1 year and have been using leaded fuel mostly as unleaded is not always available,and where available the octane rating is 95 not 97. The Haynes manual says unleaded could damage the 02 sensor, and I am quite sure will long term mess the catalytic converter. Emmission control is not such a big issue here in SA (most cars do not have cat converters here)as there are a lot more important social & other issues than the green-house effect here.So if the cat converter gets wrecked without any adverse effect on the car performance that is ok.
Will unleaded wreck the O2 sensor long term? Would it be better for the car to use unleaded 95 octane rather than leaded 97 down here at the coast?
This is an 84 model so I assume the previous owner had the same problem finding unleaded.
Don't know whether its sensable to introduce a second topic in the same thread, but has anyone out there fitted any alarm warning for oil pressure and engine temperature,and how was it done?

944S Boyeee · 04-24-2003, 07:41 AM

Did you say unleaded could damage the O2 sensor?

I always thought using leaded gas in these cars was a bad, bad thing?

944S Boyeee

Pike · 04-24-2003, 08:15 AM

I have heard leaded gas destroyes the o2 sensor and the CAT. But really, did you say the octane rating is 95!?!? I am not sure where I can buy gas like that. Our highest is 91 I think. When I get around to driving mine, it will be getting 87 or 89. It seems to me that your car would be more than happy to 'only' run on the 95. just my $.02

ilikemy944 · 04-24-2003, 11:08 AM

Pike - our gas is measured differently than theirs... I think their 99 is around our 93.

Dave951M · 04-24-2003, 11:30 AM

Lead is bad for the O2 sensor and the cat. The effect on the O2 is cumulative, finally ending with failure of the sensor. The catalytic will eventually stop up, as in blocking the exhaust system almost totally. If you have to run this stuff, remove or "rod" out the cat. Either get a test pipe or take the cat off, take a steel rod, reach down into the cat and shatter the element. Be careful to get out all of the pieces, reinstall the "gutted" cat. HTH

Makis · 04-24-2003, 12:53 PM

Are you sure you have a CAT and O2 sensor? I think 1984 cars in Europe came without a CAT and were designed for using leaded fuels. Either way the engine will be better off with leaded fuels if you can get them but you need to get rid of the CAT & O2 sensor if you have them.

Roger Hall · 04-24-2003, 04:01 PM

I will damage the cat and O2 sensor. You dont need a cat for your car to run propoerly. Just gut it. I am not sure about the O2 sensor on a 944 though. On my 924 I can disconect the O2 sensor without any problems. It depends and the computer some just ignore the lack of an O2 sensor. Some will run rich if the O2 sensor is diconected.

Paul Glasson · Paul Glasson's Garage

I see I wrote my leaded and unleaded wrongly in places. My problem as most people picked up was having to use leaded. Even in lower compression ratio cars such as the VW beetle I had in the old days I used to get 'pinking or pre-ignition' from using 95 instead of 97 octane. At higher altitude in Johannesburg they can get away with 95 octane. I was in the states for about 9 months in 1981 and cannot remember what the octane rating was.I am interested to hear what the rating is in the UK.We sometimes refer to super (97) and premium (95) and of course it is called petrol not gas. Gas is something in the vapour form, not liquid.
I am interested to hear from Roger and Makis that my "tractor" can run without the O2 sensor. My Porsche agent wanted to change the O2 sensor when I was getting stop/go cutting out problems, but it certainly was not a rich running problem. However that turned out to be a reference or speed sensor bad plug connection.
The tractor is fully imported here and the booklet that comes with it refers to the O2 sensor and cat so I assume they are there.

AFJuvat · 04-24-2003, 10:49 PM

Leaded will destroy the emissions system of the vehicle. (O2, CAT, etc)

That said, if you are using the European specification 944, you do not have a O2 sensor.

If you have a catalytic converter, you can remove it\bypass it. Do not recommend using leaded fuel with a CAT, it can clog up very quickly and cause severe engine damage.

AFJuvat

Baza · Baza's Garage

Check you VIN number if it has the letters ROW (rest of world) it will be the same as my 944 here in Australia. It should not have a CAT or sensor and they will swing both ways with no problem so long as you use the higher octane petrol, the higher the better. If you do have a CAT lose it. I had a sticker on the fuel hatch which read only use super (leaded) as unleaded was not in this country at the time, when it fell of it said use only 93 octane fuel our highest rateing. I personaly use 93 but I also use Super (leaded) when I can't get the good stuff usually in the country with no problems or pinging. And I don't have a CAT and mine is ROW.

Hope this helps

Alex Cook · 04-25-2003, 10:01 AM

Paul, the octane rating we get in the UK is 95 for ordinary unleaded and 97 for super unleaded (except Shell who make a 98). The US octane ratings are not comparable, I believe 93 in the US is equal to 98 in the UK.

I'm with Porsche_postie on the cat issue, unless your car is a US model. As far as I know, cats were not introduced until 1990 for RoW cars.