Best Gas

I know this topic has been talked about countless times, but I was wondering whats the best brand gas for a Buick (3800 engine) and what gas mileage do other drives average. I know gas comes from the same place (there is a refinery in my city), but they add different additives for each brand. The reason I'm asking this question is because it seems that when I put Exxon gas in my car I get worser mileage than when I put an off brand ( mapco, local brand) into it. This week I seems to have really dipped, granted I was doing 100mph for about 5 minutes :grinyes: (got off work late exams that morning), but I don't think it would dip like that. I've recently changed the o2 sensor (Bosch, bash me later) but I was average 22mpg with the new o2 sensor and mapco gas, but with the Exxon gas its like 20mpg.

This week I seems to have really dipped, granted I was doing 100mph for about 5 minutes. I was average 22mpg with the new o2 sensor and mapco gas, but with the Exxon gas its like 20mpg.I think you answered your own question, the 100-mph blast cost you 2-mph! If the "off brands" get better mileage, that is what you should use. Of course, none of them will do very well @ 100-mph! :shakehead

Today I was checking my engine compartment and found a cracked vaccum hose. It was the hose that connected from the throttle body to the EVAP canister. It was split were the rubber connects the two plastic hoses. I taped it up with som electrical tape (quick fix for now) until i get some money. My question is, could that be a significant cause for reduced gas mileage since the EVAP canister feeds gas vapors back into the intake manifold? Or could I have just fixed a slight vaccum leak?

Both on the EVAP system. Did you know that while you are normally accelerating up to 55 MPH you are only getting 3 to 6 miles per gallon.

How airlaines are going broke!! A 747 uses 4000 gallons to reach cruiseing altitude from take off.

Were did you get those facts from? They sound interesting. That explains why even though I take interstate mostly everywhere I go in the city I still only average 20-22mpg, but when I take long trips I get 31mpg doing 70mph.

The stop and go driving does it as well as sitting at stop light and traffic jams. Reads 0 mpg when stopped.

I have fuel usage monitors on both my DTS and my Montana. They register instant mpg, average mpg, total miles left to drive according to fuel usage as well as gallons used.

Even driving into the wind, with no speed changes, can rob you of 3 to 6 mpg depending on wind speed. ( not just a breeze )

I don't know why I didn't realize that. I forget that most newer cars (some older ones) have the i fuel monitor reading system. Thats one thing I wish I had. My dad has the fuel monitor on his astro van. I've seen it register 2mpg accelerating up a inclined street.

You can monitor your best mpg engine performance cheaply by installing a vacumn gage around the dash somewhere. They are small like the amp-oil gage systems you can buy. Just plugs into a direct manifold vacumn port with a rubber hose. Shouldn't cost more than $ 10 -12 and is simple to install. Hardest part is figuring where you want it.

The closer you can keep the gage to 17 in/hg or higher the better mileage you are getting.

That is one of us older mechanics tricks. Also helps diagnose engine problems as a second benefit.

Both on the EVAP system. Did you know that while you are normally accelerating up to 55 MPH you are only getting 3 to 6 miles per gallon.

How airlaines are going broke!! A 747 uses 4000 gallons to reach cruiseing altitude from take off.

i was wondering about that because when i used to go to work i would drive like 5 blocks from my house onto this little phony type of highway for about 4 minutes doing 65 mph to and from 6 days a week and i would hardly waste any gas, but now that i work in the city with all the stop and go(hate it hate it hate it) it seems like im putting gas into my car all the time. also when gas was 3.21 a gal it took me 50 dollars to fill up, is that normal for a car my size,88 buick park ave? there were people with cars like impalas,malibus,grand marquis that took less to fill up on 3.21 a gal.


as for the first question about gas stations, i go to bp(amoco) which is about 4 cents more than this local brand, but my gas always seems to last longer with the bp brand. i dont know if its true or not, but theres a rumor that the local brand mixes water with their gas to stretch it out :eek:



also i think my car likes 45 mph the most out of any speed. sometimes when i get it up to 25-35 mph it will transition almost instantly to 45 mph and just glide like a dream on empty city streets(night time) do you think constantly going at 45 mph hurts/helps gas intake(sometimes my foot wont even be on the pedal and i can coast at 45 mph for long periods of time if uninterrupted)

Usually the larger the vehicle, the larger the fuel tank. I think it has to do alot with having more room underneith the vehicle. I just spent $80 bucks to fill my Montana and it had almost a 1/4 tank when I started.

Rumors are just that. If water was introduced, it would fall to the bottom of the underground tank as it is heavier than gas. Also the tank pickup pipe does not rest on the bottom of the tank otherwise the first people to get fuel would get nothing but water and no one would ever go there again. I use the off brands all the time and have had no problems except once when a station had a leak in the tank cover and rain water built up to the bottom of the pickup tube. Actually you will get fresher fuel from a station that sells for less than the name brand because they move more fuel than the high priced stations.

CAUTION: Never by gas at ANY station where the tanker is dumping fuel. As he is dumping, he is stirring up dirt and water off the bottom of the tank. Give them a day to let the sediment fall back to the bottom of the tank. This will save your fuel pump and filter alot of wear and tear.

Every car has its sweet spot where mileage is at its best. That is one reason the speed limits on state highways is 55 for the average. Mine likes 65. Steady speeds does not hurt an engine as long as you have some variations here and there. My Caddy DTS is considered an old mans car and you see them practically crawlling along when they drive. The Northstar engine does not like that because it is too sophisticated. It is made to run at higher RPMs than the typical driver. I currently have 167,000+ miles on it and it runs like a
chettah.