Getting used to gas

In my family law class, the prof handed out an article on a prenuptual agreement which included as a provision “We will never allow the gas tank to get below half-full, and we will only fill up at Chevron.” The husband explained that the car was “used to” Chevron gas. This sounds like a UL to me.

Does a car engine become accustomed to a certain brand of gasoline? Do all gas stations under a particular franchise get their gasoline from the same supplier? Are there differences in the refining process from one refinery to another?

I’ve heard this too, but I don’t know if it’s true.

Someone posted a pretty thorough explanation of the workings of gas suppliers on a question I asked in GQ – “Would this work (gas prices)?” If you can find it (it’s not too old), it would answer a big part of your question.

Otto, I couldn’t help but wonder was this about the story of the newlywed couple that were featured on Dateline NBC. It really was pretty funny and sad at the same time. The woman was SO proud that she got her new husband to change his mind ‘just for her’ that she could wait till it was three quarters empty now before filling up again!

I can’t imagine that a gas tank could ‘know’ anything, other than is it full or not, or the octane level is different. My car runs best on 87, but my husband’s car is an '84 and needs a higher octane so that it doesn’t rattle so much.
I’ve also read in my Car Care Book that it isn’t good to let the car get close to empty before refilling as the impurities sink to the bottom of the tank and when you fill up it distributes the particles, but I even see holes in that. The force from the tank filling no matter how much was in the tank, seems like it would distribute those particles if they are really in there.

It would seem that refineries would all be the same, but I’m sure no expert. It just seems to be logical, and that franchises most likely would be using the same refinery, as in McD’s being franchised but using the same place to get their fries, to insure similiarities and texture. But, this is just a guess.


“Um, according to who? Nothing more than a high brow troll, though occasionally the bi polar personality swung in a constructive direction on innocuous topics.” Omniscient

I’ve been told that junk (the occasional piece of dirt, twig, etc) tends to build up in your gas tank, the junk tends to float on top of the gas, and letting your tank run to empty tends to result in that junk getting sucked into your gas lines. The gas filter catches almost all of it, but then the junk clogs your gas filter.

At least, that’s what my boss told me once after I had to have my car towed to the garage to get the gas filter replaced. I have no idea whether he really knew what he was talking about.

I’ve always assumed that there is some ususable fuel in a “sump” (like in airplanes). The dirt, rust, etc. would sink into the sump and would not be picked up in the fuel line. I’ve run out of fuel a few times (on the motorcycle – there was a problem with the fuel selector that would draw from the “reserve” position regardless of how the selector was positioned) with no ill effect to the engine. If you do get grit into the fuel line, it’s a simple matter to replace the fuel filter.

You should run the lowest possible octane in your engine as long as it doesn’t “ping”. Most modern cars will run fine on 87 octane, but I’ve found that older cars (and even the motorcycle) would require higher octane fuel on hot days to prevent pinging. Higher octane also helps if you have a tendency to stomp down on the accellerator, especially when it’s hot. Using a higher octane than you need is a waste of money.

My 1.9 cents.

“I must leave this planet, if only for an hour.” – Antoine de St. Exupéry

Are you a turtle?