Gas Brand and MPG

I have used both AAFES (cheap gas sold on post) and Chevron and have not noticed any MPG difference. I have about 2000 miles straight with AAFES gas and 2000 on Chevron. The main reason I switched to Chevron was because it has more detergents (ie Top Tier gas) to try to keep the engine cleaner.

 

I've been using mostly Mobil, and sometimes Exxon. Seems pretty good
except took forever to get summer fuel!

Then I tried Shell and my mileage went up like 1 mpg.

Today I filled up with Hess, and mileage went down almost instantly by over 8 mpg.

July 11 new info: I have now used about half this tank, and notice some interesting things:

1 driving 65 mph mpg is 47 to 48 only a little below normal.
2 driving 40 mph I get significantly lower bar graphs with max ones (other than full coasting) tending to be 60 mpg instead of 70 to 80 mpg.
3 I notice less power subjectively on accelerating.
4 No matter how I drove, even going under 50 mph more than usual, best I could do is get mpg up to about 52 mpg. My normal routes mix I was averaging over 56 in my last tank.

Today I tossed in some Techron and an octane enhancer. Drove around my normal routes and got 50 mpg at 70, and back to normal bar graphs for 40 mph routes. Average has climbed to over 53 now, with tank half full. So with normal commute I think I can maybe reach 54 at least by the time the tank is empty! After half a tank, the average is slow to move!

So I suspect my gas was just a bit low in octane maybe, not enough to notice pinging, but enough the car had to compensate in a way that cut mileage. OR maybe it was water?

Not sure why the effect was greatest at light loads, or slower speeds???

JUly 15 update:

Well the additives didn't keep it going quite as good, as my tank got close to empty, and I wound up with like 52 mpg for the tank.

Back to Shell and I'm back to 55 mpg on my test loop. So my normal commute routes should be over 56 as there is more 55 mph and less 65.
At 44 miles on this tank, but the difference is quite dramatic.

With nothing added to the gas I was getting most bars at 52 mpg at 65 mph even some up hill sections.

I expect 60 mpg might be possible if I could just fill up with real gas instead of the reformulated oxygenated stuff. Anyway I'll stick to brands that work best, even at a few cents more per gallon now.

 

Here in NJ I have found over the years in many different vehicles no difference between brands -- EXCEPT for price. You have to remember that around here ALL the gas comes from the one refinery in Linden. I buy the cheapest gas I can find - BUT only from a high volume station to avoid sediment and stuff. You are much better off doing that than buying from a name brand outlet that pumps very few gallons -- that gas sits and is usually not as good.

 

There are also stations that buy gas "out of code" that the major companies won't sell anymore with their name. These stations are no-name and generally FAR lower than anyone else's price, including the other no-name's (independent stations selling regular gas). These are good to avoid.

All the gas can come from the same refiniery but that same refinery can make multiple blends (remember how they complain how many types of gas they're forced to produce?) Also, additives are added after-the-fact based on the brand's specificiations, so gas coming from the same refiniery can have different additive versions going to each different retailer.

To see the difference in MPG for a different brand, you'd either have to drive totally identical conditions in each tank or use the average of multiple tanks of the same brand. I almost always use the same brand and notice differences in mileage as high as 4MPG between tanks, likely due to conidtions/driving style more than anything. The average is consistent though.

I wouldn't expect much difference between brands if you average multiple tanks, I fill up TopTier (mostly Shell in this area) since it costs about the same and the car manufacturers are more credible than gas company advertising about additive quality.

 

Your point about additives can be true. I have however noticed no-name tanker trucks deliver to Shell or Mobil station and then pull across the street and deliver to the Brand-X station. You know they are all getting the same gas when that happens.

 

I just purchased a 2007 Prius earlier this week (my first new car, at 27, and my third Toyota).
The first tank of gas delivered only 41.11mpg as an average. I just put in 76. I'm wary of cheap
gas, but I'm also looking for the best millage. I'm thinking of obtaining the EV only option from
Coastal Tech. Will this deliver additional fuel savings? There are lots of places I'm going 30mph or under.

Also, I'm sure this is the wrong forum, but what options do I have for bike racks?

Thanks,

Paul

 

Chevron is by the far the best gasoline on the market - bar none. The reason is the Techron additive that is used in their product.

All gasoline brands are the same (they come from the same oil fields and refineries.) However, each brand has its own additive package. For the Walmarts and other low cost marketers, a generic additive package is put in which meets minimum federal standards. For other name brands (such as Chevron), they provide their own unique additive package which equals or exceeds federal standards.

The additive package is important to keep fuel injectors clean and to minimize the amount of carbon deposits within the combustion chamber. By keeping these components clean, the combustion process is maintained at its peak efficiency (resulting in the best gas mileage possible). (The injector sprays the gasoline into each cylinder in a stream that looks just like your windex or 409 spray pump - Imagine if that sprayer nozzle was dirty or partly messed up: the spray stream would be more in droplets or pointing sideways) In a gasoline engine that would make it harder for the gasoline to mix thoroughly with the air that's in the combustion chamber.

It is well established that engines that use techron on a regular basis are cleaner as evidenced by technicians who take the engines apart (ask a good mechanic at your dealership - he can usually tell if a car has been running on Chevron or not).

To get the benefits of the additive package requires that you run several tankfuls of a gasoline through the engine. The additive is not magic - it takes time to clean up whatever carbon deposits are in the engine. Likewise, a tankful of cheap gasoline will not instantly foul your engine.

On a slightly unrelated topic: Octane ratings. To save money, don't buy any higher octane rating than what your car manufacter recommends AND you usually do not hear knocking from the engine (due to load or an old engine). To the extent that you have a clean engine will make it easier for you to buy a lower octane gasoline (carbon deposits in the cylinder will tend to preignite the fuel resulting in knocking).

 

I used to shop around to buy the cheapest gas and did not notice any difference attributable to brand. Now that there are 3 Shell stations (they were Texaco) with competetive prices in my area I got Shell's Citibank MC for the rebate.

 

I've only put RACETRAC gas in my prius.. but then again i'm only on my 2nd tank. It's the cheapest gas around so i'm sure it's not the best. I'm going to try chevron or shell on my next tank after seeing all of the posts about it on here. but so far racetrac hasn't been bad.. i'm avg. 52.2. been unusually cold in atlanta lately.. highs in the upper 30's.. lows in the upper 10's ready to see what i get in the summer with highs in the upper 90's