So one of my agents just took delivery of a new Porsche 911. Its not a Turbo, just a plain (if you can call it that) 911 Cabriolet. She (and I) were surprised that it requires 93 octane, I have never seen a car that specifically required 93, all of my cars that required premium have all been 91. Around here, 93 is everywhere but in other places sometimes all you can find is 91. The dealer told her she HAD to use 93. That doesnt make sense to me, what if you lived in CA for instance and there was only 91?

 

The manual should confirm this?

 

I find that surprising. If I recall correctly, California pretty much doesn't even have 93 anywhere? I know it's hard to find in my state as well - seems only BP and Gulf stations have it.

I suspect the dealer just means that it needs premium fuel.

 

what i figured but even that was tough to find lol

 

My Cayenne says MIN OCT 93 on the cap but we don't have 93 (or its very rare) so I've been filling 91 for the year that I've had it with no issues.

 

No issues getting 93 where I live. Only use Mobil or Shell.

I’m sure ECU will adjust to lower octane - plenty of Porsches in Cali where there is no 93 gas.

 

91 is perfectly fine. My 911’s both said 93 on the filler cap, and both ran fine with 91.

 

Exactly, several places you can’t get it. Lots of Porsches in CA...

Manual says 93.

 

An octane-booster might help, but I'd use it sparingly, as not all of them are legal in every state, and there are sometimes risks to their use. This web-site give some good tips:

https://www.autoguide.com/top-10-bes...rs-you-can-buy

 

I did some googling and came across this post on Rennlist. Screenshots from the owner's manual:







Basically 91 can be used, but if it is, the car is not to be driven at full throttle.

If 93 is not available, Porsche sells a fuel additive that can be mixed with 91. Porsche P/N for the fuel additive is 00004320902.

 

What a huge PITA!

 

My 2000 Porsche Boxster S +has the oe knock sensors that automaticly retard the ignition timing at the 1st sign of pre-ignition. When I rebuilt the engine with bigger cylinder bores, the compresion ratio increased to 11-1 I have never heard any knocking but it definitlety is faster with higher Octane that I find occasionly.

 

https://en.wikipedia.org/wiki/Octane...,_MON,_and_AKI

 

Not driving at full throttle is only referring to 87 Us grade fuel. 91 US grade is marked as alternative fuel.

https://en.wikipedia.org/wiki/Octane...,_MON,_and_AKI

91 RON (europe) = 82-83 MON = 87 AKI (US)
So, in a pinch, 87 regular can be used.
While recommended fuel seems to be 98(EU) or 93 (US), an alternative grade of 95 (EU) and 91(US) is also acceptable.
I guess, alternative is probably fine reliability wise, but it wont give the HP numbers or throttle response they had in mind when they were designing and testing the car.

 

I've had to run 91 in my 2015 TTS with no side effects I could tell. Normally I try and find 93 if at all possible but some stations in SE WI only offer 91. With standard driving (non track days), I cant imagine it would hurt anything...perhaps just lose a few HP. I guess driving around with "only" ~550hp will suffice