Wot fuel

[luke]

Following advice from the mechanic (Porsche expert) who lives next door to Shirleys Garage, I've been filling up with regular unleaded. Engine seems to run well & plenty of power etc, but not having run a 993 before, I've not really got anything to compare it with.

Is it worth switching to 'super', or filling up with Optimax once a month - any thoughts?




Migration info. Legacy thread was 13790

 

[willisit]

I use nothing but super or optimax... the car runs great on the stuff!

Migration info. Legacy thread was 13792

 

[bosch]

Likewise I only use Sheel Optimax or Super plus unleaded, the theory being it burns better and keeps the chambers in tip top condition (Evo mag did a test on this a while back). I do notice the different in mid range pull.

Migration info. Legacy thread was 13793

 

[Toby Armfield]

isnt the 993 designed to run on 98 ron fuels - i think only optimax is 98 ron unleadeed - reg unleaded is 96 and the other 'high performance' unleaded fuels i've seen are 97 ron. Running at a lower octane rating will cause the car to reatrd the ignition to prevent knocking or pre-ingnition i believe - i'm sure someone else can confirm or not!

Migration info. Legacy thread was 13796

 

[Carrera]

The anti-knock sensor will retard the timing to prevent pinking when 95RON fuel is used. Thus when Optimax is used the engine feels much better.

Migration info. Legacy thread was 13801

 

[willisit]

Optimax is supposed to be 98RON but it's not guaranteed at that - only 95RON. Only SuperUnleaded is guaranteed to be 97RON as advertised.

Migration info. Legacy thread was 13803

 

[Vic]

Shell Optimax FAQ's

http://www.shell.com/home/Framework?siteId=uk-en&FC2=&FC3=/uk-en/html/iwgen/shell_for_motorists/fuels/questions_answered_0312_0921.html#6

They claim Octane is "greater than 98 RON".


Migration info. Legacy thread was 13808

 

[Toby Armfield]

From shell.co.uk

<Sorry previous link not available after migration>

Shell Optimax has the highest octane specification of any petrol available on UK forecourts. It is greater than 98 Research Octane Number (RON).

So thats false advertising if it aint!





Migration info. Legacy thread was 13810

 

[Carrera]

I remmember reading somewhere that other superunleaded use different chemicals from Optimax to boost the octane, and there was a claim that it may even cause long term damage to some engine. I don't know how true that is or whether there's any evidence to back that up. I never use anything other than Optimax for my 993 since Optimax was introduced, and the car has been running great!

Migration info. Legacy thread was 13819

 

[willisit]

I'll try to dig out my evidence - it was researched thoroughly on my Calibra forums. Optimax was found to be the weakest..

.. with that said, I use it regularly because I'm happy to believe the hype and it DOES appear to make a difference. It certainly isn't hurting the car!

Migration info. Legacy thread was 13820

 

[Dunc]

I work in the oil industry for one of the major players and I'd take their RON values with a pinch of salt. As for my 993, I run it on regular unleaded with no problems at all.

Dunc


Migration info. Legacy thread was 13821

 

[Phil M]

This was debated to death on Scoobynet as the Jap imports are designed to run on 100RON fuel. IIRC Optimax is normal 95RON with and additive which degrades over time, therefore Optimax could be anywhere above 95RON.

There wasn't a definative answer but the general consensus was Optimax is good and cars run a bit better than on normal 95RON. The other thing that struck me was the view towards supermarket fuel, it wasn't as purified as Shell/BP.

Phil


Migration info. Legacy thread was 13860

 

[Paul Strong]

One thing that stuck in my mind from the Optimax debate on Scoobynet (or maybe it was the IWOC Impreza list) was that someone talked to a techie at Shell and was told that the typical rating of Optimax was 98.6 RON, hence the "greater than 98 RON" claim.

Migration info. Legacy thread was 13879