crw

Local gas stations carry 90 Octane (no ethanol) or 93 octane (has ethanol)

Which would be a better choice.

IainM

I’d say if you drive regularly then ethanol is not such a concern. If the car is parked for months at a time then the non-ethanol would be better.
(edit) it will be hard to completely purge your tank of ethanol gas if you’ve run it before. Each fill just dilutes it, maybe a couple of tanks would flush most out.

Verboden

Agree with IainM. Also if you do go the 90 route the detonation risk is highest with low RPM high throttle situation. Good reason to rev away.

L39E

I only use Rec 90 / non-ethanol gas in my air cooled cars.

LexVan

Buy the highest octane you can find from a busy national chain gas station. Don't over think this.

L39E

This is from the Porsche UK website

Greg Bell

On this side of the pond I can easily buy 98 Octane - which I favour - or you sometimes see 100 Octane. I've always wondered how a 'chip' would perform on these higher octanes.

fatmike

We use a different octane calculation in the US. We use the (R+M)/2 method) so our 93 is like your 98.

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fatmike

Again, different scale. That's like putting 86 or 87 in your car in the US.

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MarinS4

Try E30 with a tune. That would really wake the engine up!

So much to say on the subject but simply put both extremes of E10 and E85 have short comings. Since this is a E10 question I’ll focus on that. The trouble with such low blends is phase separation. When the moisture content of the fuel exceeds the ability of the E10 portion to hold it phase separation occurs. This is the foundation of all the ills most experience with ethanol. The higher blends like E30 and above don’t have this problem.

When considering E10 fuels one must think about their environment. Cold damp UK is a completely different problem than somewhere like Arizona.

JasonAndreas

We have close to 20 years of running data from the 964 and 993 using E10 in the United States and it has been a non-issue.

JParanee

90 octane is not something I’m interested in using in any car I own

L39E

To each their own. E10 is not something I’m interested in using in any air cooled car I own. Here in the mountains of Utah, I use ethanol free 88 instead of the 91 (highest octane offered) in my older cars. At 7,000’ altitude it is quite fine, as the air is less dense and the engine makes less power. I don’t want ethanol gas in my tanks while my cars are in hibernation for winter. Even at sea level in Florida, I use ethanol free 90 over 93.

To the OP’s question, it really depends on your use. If you drive your car frequently and it never sits or is stored for the winter, ethanol 93 should be fine. If your use is seasonal, I would recommend avoiding ethanol gas. Pure Gas is a great app that will show you the nearest gas stations with ethanol free gas.

pp000830

I always go with the Octane rating the factory suggests and if one doesn't run their car often add fuel stabilizer or seek out gas with the proper Octane rating to fill the tank.

Also, there has been lots of talk of ethanol causing problems, however, I have not seen a discussion recently where 993 actually has experienced such issues. If someone would describe a personal experience where ethanol was the proven root cause for a fuel system problem on a 993 please reply. Key here is proven not suspected. Also how it was proven would be a great addition.
Andy

F8Driver

This from my Bimmer. West Texas, oil country, and nothing over 91 octane. I normally use 93. Saw a significant drop in MPG. Car ran fine, just about 10% less MPG. Only other time was a fillup in Iowa, the navel of the ethanol universe. The supposed 93 octane, 10% ethanol (I think much higher) gave horrible mileage. The ethanol scam is the one that bothers me most. The politicians and producers love it ... and for good reason ... but it's not good for the car owner.