Junk Food for the Turbo? Or are we just too anal?

[Looking_for_911]

Sometimes I feel like I should just keep my mouth shut, and some times I feel like yelling WTF?
I just saw a guy pumping gas into his mid-80-ish 930 at a Race Way/Race Trac convenience store.
I have read so much on this forum about and listened as qualified 911 techs have talked about fuel/octane/detergents/additives, etc. and when I saw that it amazed me.
True, it's not my car. But why would one want to use "cheap" gas in a 911/930... especially with the turbo and all.
Are we just wasting money on "quality" gasoline? Is my search for non-ethanol- laced fuel just a waste of fuel and time? If one uses 93 octane from a convenience store is it as good as using Shell/Chevron/Texaco, etc.
Of course, one could say he was in a pinch and could not make it two miles down the highway to a better station, but there was a Shell convenience store across the street. And, we're not supposed to let our tanks run dry, are we?
I don't mean to disparage him or his car, he's local, that's why I'm not mentioning the color or unique license plate he had.
But,
WTF?

[emcon5]

Originally Posted by Looking_for_911

Are we just wasting money on "quality" gasoline?

Pretty much.

[DW SD]

I think the local stores buy their fuel from the big refineries and it probably makes zero difference. That said, I believe the octane ratings do matter.

Have you noticed tankers with no logo unloading fuel at the local Chevron (for example)? I see it all the time.

Doug

[mtnfir]

A few months ago when we had the gas shortage and premium became nonexistant and 87 octane went to 4 bucks, I did some research. There is basically one pipeline coming into my neck of the woods. All of the gas around here comes from that pipe. Don't think it matters much where you buy it, as it is the same stuff. But I am not an expert.

[teenerted1]

ethanol is bad for CIS systems
but good luck on finding any with out it in most states now.
if it is a busy station you know the tanks are getting filled often that helps against water build up. if you drive often all the ethanol will do is kill your milage and mabe the plastic in your fuel system. unless you have some crazy race engine pump gas will be fine.

about the only place i wont buy gas for the p-car is ARCO. other than that most of the rest seems ok

[Looking_for_911]

Originally Posted by DW SD

I think the local stores buy their fuel from the big refineries and it probably makes zero difference. That said, I believe the octane ratings do matter.

Have you noticed tankers with no logo unloading fuel at the local Chevron (for example)? I see it all the time.

Doug

Around here those truck usually have a distributor logo on them.... and I have wondered if the distributor is actually selling premium or just regular in the premium tanks. When I do see a non-logo truck delivering somewhere I try to make a mental note not to buy gas there.

[304065]

Perhaps it was a 912 with a body kit.

[uwanna]

A month or so ago, Charlie Gibson did an ABC one hour special on oil and gas. He visited a huge gasoline distribution terminal. The man that ran the terminal said that all the gas loaded onto delivery tankers, logo-ed or not, came from the same pipe. Only difference was the octane pipe they loaded from! He emphatically reiterated that the gas was all the same, whether it went to a discount station or an Exxon/BP/Mobil etc. The only difference between the "Bigs" and discounters is the size of their advertising budget! How many folks are putting 93 octane into their family cruiser, because the oil company ads claim it's somehow better for their car's performance, and they think they are giving their car a treat. When in fact their car was designed for and runs best on 87 octane, and some research suggests that 93 octane may be detrimental the their engine, never mind a waste of money. Advertising IS VERY POWERFUL!!!

[James Brown]

and the big ones pump a small amount of there additive into it. thats the only differance. (pumped in at the terminal to make it cheveron, shell, mobil, ect.) however, the octane rating does make a defferance.

[cgarr]

Originally Posted by john_cramer

Perhaps it was a 912 with a body kit.

Hey now, wait a minute, I have to run 93 in my 912 and its not because its fast

But, maybe his turbo aint working?

[Porsche-O-Phile]

Ethanol sucks. Keep it out of any car you really care about. There are ways to split it out of pump gas (google it). A little anal/labor-intensive, but not absurd for an only occasionally-driven car.

If you want a really good, boost-able blend, use straight (no ethanol) gasoline with a good high octane rating (either 91+ or race gas) and add toluene or xylene. I used to do this in my 951 when I'd turn the boost up and it worked wonderfully. I think the maximum proportion was something like 1 part tol/xyl to 4 parts gas by volume, but I might be getting that wrong.

[rsa]

Here is the truth. Exxon makes 2 grades of gas. Regular and premium octane gasoline. It is then pipelined to substations for delivery or the delivery trucks fill up at the refinery. If the gas is to be delivered to a Kroger/non name brand station, it is delivered with out additives. If it is to go to say a shell station it is Exxon manufactured gas with shell additives. And so on. Also, if it is the mid octane gas, the tanker is filled half with half premium and half with regular octane fuel.

[Canada Kev]

Originally Posted by rsa

Here is the truth. Exxon makes 2 grades of gas. Regular and premium octane gasoline. It is then pipelined to substations for delivery or the delivery trucks fill up at the refinery. If the gas is to be delivered to a Kroger/non name brand station, it is delivered with out additives. If it is to go to say a shell station it is Exxon manufactured gas with shell additives. And so on. Also, if it is the mid octane gas, the tanker is filled half with half premium and half with regular octane fuel.

That's pretty much bang on.

Originally Posted by mtnfir

A few months ago when we had the gas shortage and premium became nonexistant and 87 octane went to 4 bucks, I did some research. There is basically one pipeline coming into my neck of the woods. All of the gas around here comes from that pipe. Don't think it matters much where you buy it, as it is the same stuff. But I am not an expert.

Yup. Even diesel and the different grades of gasoline share the same pipe. When they want to switch the different types of fuel, they just start pumping in the new stuff. The receiving end knows how long it takes to get there and before it is due to arrive, they start pumping the fuel to a "waste" tank. There will inevitably be some mixing of the fuel types in the pipeline, so they pump quite a bit into that tank. Then they sample and test the fuel. If it is what it's supposed to be, it goes into the tank for that particular fuel. The fuel in the "waste" tank gets pumped back to the refinery to be re-refined.

[83-911SC cab]

I used to deliver gas to stations and businesses for a local oil company for about 13 years. Yes all fuel comes through the same pipeline to each fuel storage terminal. Once at the fuel terminal the gas goes in to different storage tanks dependent of the grade of fuel. Only during the loading process in to the delivery trucks do the fuel additives get input in to the fuel.

When delivering to a branded station you went to their terminal to load the fuel. When loading the fuel you had to either input a code/ use special card to get the branded fuel to get the branded company additives. You could also get unbranded fuel from the same terminal by using different codes/ cards. With the unbranded fuels you got some additives but not the good stuff.

I used to go to HESS, Texaco, Exxon, Citgo, Crown and get their branded fuels. But I would also get the unbranded grades of fuel at the same terminals, from the same tanks at a cheaper price. The company I worked at, a local oil company, used to buy hundred's of thousands of gallons and then rent tank space from the terminal to store it. It was not like "our" fuel; was sitting in a tank all by itself. It was in a tank that held millions, it just meant that our fuel was there when we needed it.

Yes most terminals just have premium and regular and the mid-grade is blended either automatically at the terminal or by the driver when he loads it on his/her truck. Crown's premium was rated at 93 octane at the terminal but at the stations it is 92. So the drivers would actually load some regular unlead with the premium to drop the rating from 93 to 92..Duh never figured out why they just did not list it at 93 on the pumps.

Now it must be clear as mud how this stuff works huh!!

Gregg S.

[JMH82SC]

I know for a fact Super Walmarts in my area have NO ethanol in any octane. So don't joke when you see me filling up at Walmart..........

[UrQuattro]

Ok, please dont flame me for this. Im currently putting 91 octane in my 81 sc (that's the highest available in CA - and ALL gas around here is 10% ethanol... it SUUUUUCKS!!)... Anyway, i was reading the manual, and apparently it says that the engine is spec'ed for 87, ie regular... As long as I go to a good brand name that has the right additives, is it THAT bad to put regular in the car? the compression ratio is low enough, and it doesn't have a turbo, so i dunno... In my turbo quattro coupe, sure, i'd put top end and sometimes some octane booster too for the days i wanted to up the boost...

Thanks in advance...

Michael

ps. As far as mileage, what should i expect to be getting in the city and on freeway? In mixed driving, averaging about 75-85mph on the highway and driving without much aggression in the city, i seem to be getting just under 20mpg... When i took a trip up to tahoe, i averaged about 21mpg on the freeway... I dunno... I thought i'd get about 18 city and maybe 22-24 highway...

michael

[TimT]

All of the gas around here comes from that pipe

They deliver a lot of different products through the same pipe...

I think the put a slug or "pig" in the pipe that helps separate the different product.

[longhornchris04]

Brand is about the additives
Location is about the "freshness" - i.e. how long its been sitting and the propensity to have water / other crap in the tank
Octane is about... well we all know what octane is about.

Also, at least to my knowledge, running higher octane in an air-cooled motor adds a measure of safety in the event your heads overtemp. Not that you want to risk the engine letting it overheat, but overheating alone is better than overheating + spark knock. Additionally, with the less sophisticated fuel systems (i.e. Carbs or CIS), it helps protect the engine if your fuel system is running lean. This is technically an issue with Mototronic and later EFI - but modern sensors and emissions controls have lessened the effect greatly.

One word of caution about separating out the ethanol -- ethanol is often used as an octane booster... remove it and the fuel's octane rating will go down.

[kenikh]

People give me sh-t for buying Arco gas. Little hint: I have never seen it make a bit of difference and all stations get their gas from the same refinery. As long as the tanks aren't leaking, you are good to go.

On another note, ethanols octane rating is 110. That's why the e85 guys make sick power.

[Porsche-O-Phile]

Ethanol also eats rubber seals and hoses.

It also has a way different stoichometric ratio than gasoline. Gasoline is 14.7:1 whereas E85 is something like 6:1. Enough ethanol will throw off the stoich and mean you have to burn a lot more of the blend to get the same power.

E85 is pure crap. I try to avoid it wherever possible. There's no upside to it. If you really want to run a crazy-boosted engine, then design the entire thing around methanol with the appropriate injectors, lines, tanks, fittings, etc.