hry_glb

So, I usually use Shell V-Power, then tried 76, which I think feel a little bit better. However, I realized I got less mpg with 76. I'm trying to get people opinions about different gas brands (of course premium) and wondering what do you guys in Seattle area use?

ANIBALRX8

safeway!!!

05TiGr8Lady

Chevron
Shell
Exxon

SkyLee

Chevron only 92 OCT only

Proxi

I mainly use Costco's 92 premium gas since I can save a few more cents by the gallon. I still get the same mileage and there seems to be no difference as far as car performance if I had use Shell or Chevron premium gas. I know Costco isn't a brand name gas like Shell, Chevron, Exxon, or even 76, but I've seen a large number of high-end sedans/SUV's/sportscars chunking down premium gas at the Costco Woodinville gas pumps. If somebody trusts their $40K+ vehicle with Costco's premium gas, then I guess my RX8 should also have a drink at the same pumps. With today's fluctuating high gas prices, saving even just a few cents really helps especially when you're on a budget. Plus I've been using Costco 92 premium gas for over a year with my RX8 and I have not gotten a single once of problem from using their gas.

Rx-8 Putih

I used shell V-power when the first time got the car...then tried chevron 92 oct..I feel the car has less power with chevron..went back to V-power...then tried 76..I feel the car gets more power with 76 than v-power...I can feel the car rev quicker, and there is a change also in engine sound..sound more aggresive..I assume 76 has better octane, which makes better combustion, and more power..(my opinion )
Uses 76 since then..

FABRO

For the last 3 years I've been using 89 octane Shell/Chevron. I have about 37,000miles and no problems as of yet.

ANIBALRX8

well, if you use 92 oct all the time it does not matter what you use, they all have the same power, thats why its rated at 92 oct. the differences is some gas companies will add additives to clean your valve, etc.etc....but we do not have valve, and as for the carbon built-up, if you going us on a drive you will clean that out!!!

kristopher_d

That's not true. Arco is a 10% ethanol blend, providing less power than raw gas. However, once you get past Arco, the rest of the fuel comes out of the Anacortes refinery (a little tiny bit from Tacoma). Your only concern after that is how often they fill the tanks. As the gas sits water infiltrates the tanks, so the more gas a station goes through, the less water is in the fule, and the better your fuel economy and performance. Costco is an excellent choice. They buy from the same suppliers as everyone else, target their prices at least 5 cents a gallon less than the 5 nearest stations (there's usually an arco in there, so costco is often 25 or more cents a gallon cheaper than the average station) and don't have that crap ethanol blend.

Running lower octane is okay for easy driving in the lowlands. As load increases, or as you get up into higher elevations, you WILL run into detonation. At light throttle you'll get better economy, but the engine is designed and tuned for the slower flame front of higher octane fuels. That does not, however, mean you should go fill up with race gas to get extra power. Street engines aren't tuned or designed for it. The flame front is WAY to slow and unless you're running crazy boost levels, you wont have the compression heat that makes the 100+ octane levels necessary.

That being said, local regulations (city to city even) determine the additive mix for each gas station, so theoretically, a shell station on one side of 148th being in Redmond could have a different additive mix than one across the street, in Bellevue.

Your best bet, if you don't have a costco membership, and/or there's not a costco gas station near your usual weekly routine, is Something like this (this is for Redmond)

dozer

iTrader: (3)

chevron

jisoo26

I've used a variety of brands...Chevron, Shell, 76, Safeway, Costco. It's generally all the same although I avoid Arco. At the moment I'm using Safeway/Costco and filling regular for daily commute and premium when I wanna go have fun.

pyran

well not sure about Seattle but there aren't many gas stations in the Portland/Beaverton area that are pure gas except for Costco so that's typically where I fill up my car

Proxi

The only "hassle" I get when ever I get gas at Costco are the long lines. So I guess its safe to assume that the gas in Costco doesn't stay long in their stations' tanks (which makes it a good thing).

jisoo26

Yeah I hate the Costco lines, especially on the weekend where you end up waiting 10-15 minutes sometimes. Fortunately I don't live far from one so I try to fill up on a weekday evening or something.

BunnyGirl

Actually, there shouldn't be any stations around Clackamas, Multnomah, and Washington county that are "pure" gas anymore. By law we are required to have a 10% ethanol blend year round starting January 2008. More counties may be involved, but those are the only ones I venture into with any regularity. Of course, this means my mileage is dropping yet again. I haven't broken 20.6 mpg since the change. I used to get 23-24 with mostly highway miles regularly and 21-22 with pretty even mixed driving and shorter trips. I believe I did get 21 a few weeks ago, but that involved more highway driving. I HATE THIS CHANGE!!!

That said, I nearly exclusivelu used Chevron and occasionally Shell. However, I noticed the last few tanks at Chevron since they "remodeled" the station nearest me and also switched off the winter additive blend, my car has been running like crap with decreased power and mileage in the low to mid 18s, like the time I tried running regular in it (Bella was hungry and I was in the middle of nowhere and gas station only had regular, so no choice). I tried Shell and the car is running like she always did and the mileage immediately went back up. I don't know if it was a flukely thing until the station gets new gas, if their pumps aren't set right, or what happened, as my recent experience is pretty atypical.

05TiGr8Lady

Anyone know what the scoop is on Safeway gas? Good/bad? I've seen the tanks being filling up at my local store and it says Reinhardt on the side of the tanker. I haven't used it so far.

kristopher_d

Safeway, like Costco, has regional contracts with minimum purchases. They buy on contract until they reach their minimum, then buy what they can get at the lowest price.

Costco stations get tankers daily on average. Independent stations get tankers every 2 weeks on average. I don't know about Safeway, but I'd guess they're probably more frequent.

ANIBALRX8

I agree with you up to a point, I know water gets in to the gasoline tank in gas station so yes it will have less power, but as for the rating, if a gasoline is rated at 92 oct, it has the some power as all 92 oct.(76, safeway, texaco, cosco, ect, ect....)that is why they use the rating system. they garranty you are getting 92 oct power minimun!!!

Crazytor

i definitely say Shell or Chevron ,, , ,,,

bran702

CHEVRON NO DOUBT

bran702

ARCO

kristopher_d

Sorry, Anibal, but higher octane gas is LESS explosive than lower octane gas. Gas has a particular specific energy. Octane is a measure of Knock supression. The shell "V-Power" monicker is simply marketing hype.

Octane reduces the burn rate of the fuel in oder to supress knocking. A slower burn rate means less specific impulse against the rotor (or god forbid, piston) face. Ethanol is grain alchohal and has a much lower specific energy than gasoline. The higher the percentage of ethanol in the fuel, the lower the total specific energy of the fuel, and the less power available from it.

Per http://en.wikipedia.org/wiki/Energies_per_unit_mass
gasoline energy density = 46.9 MJ/kg or 34.6 MJ/L
gasoline with 10% ethanol = 43.54 MJ/kg or 28.06 MJ/L

for a difference of 3.36 MJ/kg or 6.54MJ/L.

Ethanol, the E component in E85 has an energy density of 30MJ/kg or 24 MJ/L

So E85 has an energy density of approximately 32.5MJ/kg or 25.6MJ/L
I say approximately 'cause I'm not sure about the biasing in the chemical forumals, so I jused a straight ratio calcuation.

kristopher_d

Finishing my thoughts:

Those numbers may not look like much, but when you consider that there's 5.3% less energy in gas with 10% ethanol, and the cost is generally 5.4% less (assuming $0.20/gal difference and $3.70/gal standard 0% ethanol gas), the cost/benefit ratio is in the ethanol blends favor. However, when the standard gas prices reach $3.80/gal (not far out by current trends) that ratio swings back in the standard gas's favor. At the same time, your big-box retailer's are selling gas at or below the %10 ethanol price, and not usually including ethanol in their blends. So it's definitely best to go with them if you can. This cost benefit ratio assumes your primary concern is mileage though. If it's HP, anything with ethanol loses out to gas without it, assuming similar octane ratings.

Now, consider the Mid-West where E85 is readily available. The E85 costs are currently heavily subsidized (it is corn based, afterall) and it's still not much cheaper than whole gas while the energy purchased is considerably less. If we were paying market rates for the Ethanol, no one would even consider E85. It would be around $12/gal (or roughly 300-400% more) for a 40% power and mileage loss.

In summary, Arco is great for commuting, where you don't really care about max torque or horse-power. In a few weeks, if they don't change their pricing, it wont be. Octane slows the flame front, allowing you to advance timing which in turn allows higher compression and boost for better mileage, torque, and horsepower. However, since you can't readily change the timing, boost or compression on a modern engine, and most modern engines are already designed around premium grade gasolines (highest street pump octane) adding more octane wont net you any gains, and in fact will likely result in a loss of power. The same goes for lower octane at high load. The spark advance at high-load will cause a lower octane fuel to reach full expansion before top dead center, causing the rotor (or piston) to lose momentum as it fights against the expanding air-fuel mixture. At light load the spark advance is minimal and you can probably get away with lower octane fuel with minimal detriment, and possible mileage gains, though not likely appreciable.

Conclusion: Make sure you get dry gas of the appropriate octane rating for your car. If you want the best miles per dollar, go to a big-box store (Safeway, QFC, Costco, etc). Can't go there, Arco is an acceptible choice for a few more weeks.

BTW, ethanol produces more particulates than raw gas, so its actually an enironmentally less friendly fuel, despite what some very famous and intelligent morons like to say.

fahrfegneugen

Stay away from Exxon, I got screwed with a whole tank of crap. Misfiring and low power.

I hear safeway is pretty bad too.

I will only buy Chevron and Shell now

hry_glb

Interesting! My girlfriend (Mazda3) has been a Costco loyal customer since the first time she got her car. I think I'm going to borrow her card and give Costco a try. I've been running around 14 mpg with 76 and 16.5ish mpg with Shell. Next > Costco.