What does your alfa like to drink: Chevron vs. 76

wc76 · #1 (**permalink**) 03-06-2008, 12:42 PM

Just thought I'd share a recent tidbit. First, a little background...about 1.5 years ago I was putting exclusively Chevron high octane in my Berlina and my average fuel economy was in the 24-26 mpg range for about 60/40(highway/city) driving. About 9 months ago a mechanic friend of mine told me I need to switch over to 76 as the addatives are better for the engine (this is California gas) so I switched to their high octane gas. When I tracked it I noticed my economy had dropped to the 22 to 23 mpg for the same type of driving. I attributed it winter driving, running rich, etc. About two weeks ago I didn't have the 76 choice and went back Chevron...24.5 mpg (bit more city driving). Hmmm...ok, after two tanks of 76...22.6 mpg for 70/30 driving. Today after two tanks of Chevron and the same 70/30...26.0 mpg. Maybe I'm missing a variable here, but on the surface it sure seems to indicate Chevron has the upper hand in the economy arena.

sh0rtlife · #2 (**permalink**) 03-06-2008, 02:39 PM

keep 1 thing in mind...time of year..summer gas and winter gas are 2 different animals...what is it..something like 10% eth in the winter 20% in the summer?..might even be higher down there in cali

**Geezer** · #3 (**permalink**) 03-06-2008, 04:54 PM

I always liked Chevron products. Haven't noticed a big difference in mileage but my cars just seem to run better with Chevron gas.

**Richard2** · #4 (**permalink**) 03-06-2008, 08:03 PM

Having boiled oil for over 25 years in a refinery setting my opinion is: Gas is Gas, additive packages are different. Refiners sell and trade to each other. All distributors buy from the nearest refinery to cut transportation costs. Refiners don't switch specifications depending on the customer and segregated tanks to customers. That costs too much in storage. They have gasolene tanks and ship out of those to all customers. The additives get added while loading the truck and some small customers accept just about any additive while the majors all have their own additives added to their shipments.

There is definitely a summer and winter gasolene, not only in the amount of ethanol used, but also in the vapor pressure and distillaton range, especially in colder climates. The BTU value of summer grade is higher than winter grade, so mileage should be slightly higher in summer than winter.

That's how it was in the refineries where I worked at anyway.

wc76 · #5 (**permalink**) 03-07-2008, 06:22 AM

As indicated in the original post, the last comparative tanks of 76 vs. Chevron were done within a 2 week period but so far the concesus seems to indicate I missed a variable. Interesting info from Richard2, I didn't realize the additives get added at the truck. So if there's no difference in gas, is there a preferred/better additive or does it just come down to marketing?

**Richard2** · #6 (**permalink**) 03-07-2008, 07:11 AM

I really don't know much about additive packages, other than they vary widely. I believe all states now require some kind of additive. Enough people are reporting differences in gas quality that there has to be significant differences, more than just marketing propaganda.

Some people don't like ARCO gas. I've used it for 4 years in Bellingham and havent had a
problem with it, but keep in mind Arco gas in Bellingham doesn't come from the same refinery as Arco gas in other areas of the country. ARCO (BP) has a refinery10 miles from here. Also, keep in mind, refiners like customers the same as any other business. They don't intentionally turn out bad gas.

alfadak · #7 (**permalink**) 03-07-2008, 02:04 PM

I have also noticed a marked difference in fuel economy in regards to brands. I am obsessive about it because I believe that large changes can warn of engine trouble. I write down in a log how many miles I get in between each fill-up and average MPG for that tank. I reset the tripometer at each fill-up and never get less than a full tank when I fuel up.
That all said, I have noticed that Chevron gets me the best mileage, followed by Shell and then 76/Conoco Phillips. ARCO seems to get the same mileage as the off-brands. I haven't noticed driveability problems, but there is definitely fuel economy differences in gas brands.

That may prove to fly in the face of economizing by not staying loyal to one brand. If the difference in mileage is 10% or more, then that offsets any amount more per gallon that a premium branded gas costs.

Andrew · #8 (**permalink**) 03-07-2008, 02:19 PM

I honestly have never noticed a difference in performance or mileage (though I do not check mileage that closely, except occasionally on trips) between brands. I tend to buy whatever's cheapest.

I will say, after some mild stumbling in my Super, which as usual proved to be in the distributor, I opened up the Italian Purolator bowl-type gas filter, which I had not even looked at in the 10 years I've been driving the car, and there was not a spec of crud in it. And I don't have any inline filters or anything.

Andrew

geh458 · #9 (**permalink**) 03-07-2008, 02:51 PM

91 proof Mobil as my first choice at home and Giant when in the southwest, then Chevron, then Texaco. I don't go to Arco or 76 since getting water in the gas for a previous car that didn't have a problem before.

**Richard2** · #10 (**permalink**) 03-07-2008, 03:23 PM

"Water" in gas is a house keeping problem either at the refinery or the gas station. Gas and diesel have to settle in tanks for a period of time in refineries before they are shipped so the "water" (actually caustic) settles out. The tanks need to be drained periodically so the caustic doesn't go out with the product. Similarly, gas stations usually "water cut" their tanks to find out how much water is in them and get it pumped out to avoid customer problems.

In eastern Canada once during a very cold winter, I was hearing a clunk coming from the gas tank every time I put the break on. I figured it was ice and added some de-icer to get rid of it. Wrong thing to do. The truck died. I got it in a warm garage and drained 3 gallons of water out! All the stations in the area were getting customer complaints. The problem was at the refinery. The tank farm operators didn't like getting out in the cold to drain the tanks

Shell used to advertise better gas mileage than competitiors. I believe this had to be due to the additive package, rather than the raw product. It's been my experience that companies periodically change additives also, so Chevron this year may not be the same as Chevron next year. Hopefully it gets better, not worse.