FourT6and2

If you have extended tank it’s anout 5 gallons of 100 and the rest 91 = 93.

M3the01

I understand the math... It's the sketchy station and the likely low volume.

Hex

I buy a bunch of 5 gallon VP C9 cans to use in my motorcycles and cars. When I want higher octane in my 2RS, I put one 5 gallon can in the extended range tank and then go fill up at Chevron.

M3the01

Gotcha, i shall source those 5 gallon cans from VP racing. Im waiting for an update from VP regarding the local station.

robmypro

1. The test engine operated on a TOP TIER gasoline averaged 19 times fewer intake valve deposits than when it was operated on non- TOP TIER gasoline. (based on the ASTM D6201 test - TOP TIER gasoline averaged 34.1mg of deposits per intake valve versus non- TOP TIER average of 660.6mg)

2. Based upon secondary research findings, long-term use of a gasoline without an enhanced additive package can lead to reductions in fuel economy of 2-4%, drivability issues, and increased emissions.

3. In most cases, carbon deposits can be reduced or removed from critical engine components1 by switching to a gasoline that meets TOP TIER standards.

4. Approximately six in ten drivers (63%) believe there is a difference in the quality of gasoline sold by retailers, yet only (12%) of drivers purchase gasoline based upon its detergent additive package. The primary motivation for choosing a particular gas station is location / convenience (75%), followed closely by the price of the fuel (73%).

5. Most TOP TIER gasolines do not cost significantly more than non-TOP TIER gasoline. The average price difference between the TOP TIER and non-TOP TIER brands surveyed was three cents per gallon over a 12-month period.

http://www.aaa.com/AAA/common/AAR/fi...ull-Report.pdf

Mattyrae

That’s what Techron is lol.

My Family and I owned a Chevron distributorship for 40 years. 😉

mchrono

OK, I'm just going to throw this out there FWIW. California is probably the single biggest GT2RS market, and as we all know, has that horrible oxygenated 91 gas. I have to think the car (at least NA spec) is specifically tuned at the factory to be completely safe on that stuff, and anything better is only icing on the cake, but not necessary to make it safe.

FourT6and2

The cars are tuned at the factory for 93 octane. Hard stop. The ECU in all modern cars can adjust for lower octane gas, however you will get the best performance running whatever octane the car is tuned for.

ThEnder

I still prefer to buy top tier gas if available, however the benefits noted above are far less applicable to engines with direct injection. Since fuel is injected directly into the cylinder, it does not wash over the intake valves in the same way it does in port injected engines, negating a lot of the benefits of the added detergents.

mchrono

I think we are saying the same thing in different ways.

Macster

With my 2003 Turbo when I had a chance to run 93 in it -- this was in Wyoming on a road trip -- the engine perked up quite a bit from how it ran with 91. Really a rather remarkable change and for the better.

In the case of your car try some 94. You can go one of I guess two ways. Use just enough 94 to bring I guess the 91 already in the tank up to say "93" which is what I seem to recall is the recommended octane with 91 being acceptable but not ideal. Or run the fuel level down as low as you dare then fill up the tank with 94 with the result the fuel in the tank is as "pure" 94 gasoline as reasonably possible.

Note the change -- if any -- from the engine and decide if you think it worth the bother of mixing 91/94 or worth the cost of running straight 94. With 94 even if it costs more than 91 if the price per gallon difference is not too great 94 might deliver better gas mileage and the difference in cost could be made up by better gas mileage. In short you need less 94 than 91.

I would not run 100 unless you were going to the track. The 100 octane is overkill but it does ensure the engine's timing will (almost certainly) not get pulled any on the track.

Be aware if 94 octane is priced too dear the gasoline may be old and the higher the octane the more impact age has on the gasoline. IOWs, it gets stale and in this case may be worse than 91.

I do not recall where I filled up the Turbo with 93 but the station was a rather nice/modern station and I make it a habit to pick what I think are busy stations to ensure getting the freshest gasoline.

As for brands what I have found -- and the Porsche techs told me this was their experience -- is generally the Porsche engines do best with Shell V-Power. There appears to be a bit more power when using this brand. FWIW, in a gasoline test in the UK Shell came out on top.

But I noticed with my Boxster when I switched it (and the Turbo) from Shell to Chevron -- the Shell station raised its prices to even above the down the street Chevron station -- that after not even the 1st tank of Chevron Supreme the Boxster engine was running better. I guess the Techron "cleaned" up the engine and this accounted for the change in performance.

I also talked this over with the techs and they reported experiencing similar results. Some said they occasionally fill up with Chevron gasoline or as part of the periodic service treat a tank of gasoline to a proper dose of Techron (from a bottle) for the cleansing benefits. The service manager pointed out to me that while the Porsche dealer stocked some other brand of fuel system cleaner and the techs could buy this at the employee discount all the service manager saw on the tech toolboxes was Techron which the techs have to buy at full price.

Might add while the Boxster engine perked up some after switching back to Chevron from Shell the Turbo engine did not. I attribute this to 1) The Boxster engine had lots more miles on it and while it ran very good I thought the miles in some way might result in a slightly less clean burning engine. 2) Besides having fewer miles the Turbo engine is more precisely fueled -- wide band O2 sensors vs. the narrow band O2 sensors used in the Boxster.

Also, the Boxster engine might have been due for a tune up. While I had the plugs changed on schedule the coils were original. There were no misfires but when I had the Turbo coils changed at around 140K miles -- not because of any issues just curious as to what if any effect this might have -- the Turbo engine ran a bit better after. Had I kept the Boxster its next service I was going to have the coils replaced just to see what if any change this had. Oh, when I sold the Boxster it had 317K miles and still had its original coils.

Another thing of note is sometime after I switched to from Shell to Chevron and in fact may have switched back to using Shell for at some point the Shell station brought its prices down some to where Shell gas was price competitive with other brands of gasoline nearby at 305K miles I had the O2 sensors replaced in the Boxster. With new sensors the engine perked up some. (And likewise with the Turbo when I had the sensors replaced at 132K miles -- there was an O2 related error code but the engine manifested no signs of any trouble -- the engine ran better after.)

More on brands. That UK fuel test found that "supermarket" and branded station gasoline performed quite alike most of the time. But sometimes the supermarket gasoline was subpar. This was determined to be from the fact supermarket gas stations were very price sensitive and shopped for the least expensive gasoline stock and occasionally would get what they paid for.

Gasoline from branded stations was much more consistent in quality.

But there were exceptions. An occasional "off" tank of branded gasoline was attributed to staleness. When the testers bought gasoline from busy branded stations the subpar gasoline was a thing of the past.

Bottom line is based on my experience with 93 in my Turbo I would definitely recommend you experiment with 93/94 in your car. If the engine reacts favorably you then of course have to decide if this is just a special occasion fuel or an everyday fuel. While I can't recall the price difference between 93 and 91 at that station in Wyoming that I don't remember suggests the price difference was rather tame. (Even years and years ago when I filled up the Boxster's gas tank with 100 octane gasoline I can recall the $6+/gallon price being around 3x as expensive as 91!)

Had I lived in that area of Wyoming I would have probably used 93 all the time at least in my Turbo. The Boxster engine even with 100 octane gasoline didn't exhibit any signs, good or bad, from the presence of the higher octane gasoline.

eldy80

https://en.wikipedia.org/wiki/Top_Ti..._retail_brands

Costco is a Top Tier brand and injectors get replaced every 2 years regardless of mileage.

Mattyrae

Depends on where Costco is getting their gas. They put it out for bid each year.

Bxstr

I try and get to Shell when I can. However, the one Shell closest to my house is still 10 mins out of my way, the other one is 20 mins from me but typically in an area that I am at. There is a gas station that is right by my house though that I frequent the most. Very busy so I know I am getting fresh gas.

Always get 93 here, but I typically can't even find 91, unless it is at a Sunoco.

hacker-pschorr

Costco here for all the engines I care about, it's the only 93 top tier in my area.