Cheap gas?

June 19, 2004 7:03 PM

Why is it that a place like, e.g., the AM/PM can sell gasoline for $0.20 less than other places around my city? Is it the legendary wash gas? Does such a thing exist? And... what does octane rating actually entail? And does it really matter?
posted by xmutex to shopping (7 comments total)

wash.... gas?

I know those words....
posted by John Kenneth Fisher at 8:09 PM on June 19, 2004

Profit margins on slurpees make up for the gas, I think.

High-octane gas in only required if your car's manual says it is. If you have a high-octane engine but use low-octane gas, it will "knock".
posted by falconred at 8:28 PM on June 19, 2004

The octane number simply depicts the fuel's resistance to detonation. High number= more resistant to knocking. Unless your engine is high-compression, turbo- or super-charged, or a rotary, you probably don't need the Premium stuff. RTFM.

Before cars had knock sensors (in practice, little piezo microphones) to retard the timing and prevent knock, engine damage from excessive knocking was more of a problem. Now, instead of blowing up your engine, you just get a slower car.

Also, most people do not know that more BTUs are in a gallon of the cheap stuff than the expensive stuff. Now you do.

It's true that some gasoline retailers add detergents to the higher-grade fuels, but unless your manual asks for the good stuff, give it the cheap. You can always add Techron (the only carbon deposit cleaner that actually works) to clean valves and injectors.
posted by trharlan at 8:39 PM on June 19, 2004

My understanding is that AP/PMs differ from regular Arco (and most other brand name) stations in that they do not accept credit cards. Credit card commissions shave ~4-6% off their gross sales. They're giving you a cut of the savings.
posted by nakedcodemonkey at 9:23 PM on June 19, 2004

Also don't put in a high octane than given by your user's manual. Doing so will in effect put extra strain on your engine and cause is to wear away faster than normal.
posted by jmd82 at 9:34 PM on June 19, 2004

For what it's worth: round about where I live, the AM/PM price is seldom more than $.02 / gallon less than nearby competing stations.

The really odd thing is that you can drive 1/2 mile and find a second AM/PM that sells for $.20 more than the first. Location, location, location appears to be the key.
posted by SPrintF at 10:13 PM on June 19, 2004

Arcos don't accept credit cards and charge 50 cents for ATM transactions.

However, any look, say at losangelesgasprices.com will show that Arco/AM/PM doesn't always have the cheapest prices.
posted by calwatch at 10:33 PM on June 19, 2004