Has anyone had their gas mileage drop when switching gas?

[zmc]

I have a 2005 Mazda 3 2.3 and when I first got it I put premium gas in it and averaged about 385 miles per tank. My husband then started putting regular gas in for about a month and a half and I noticed the car wasn't performing the way it used to. It was also getting about 290 miles per tank with the regular gas. I have since switched back to premium gas but am now only getting about 330 miles per tank. Any ideas why I lost mileage even though I switched back to premium? Also, any ideas on how to get the mileage per tank back up (with gas prices being the way they are I'm trying to maximize my mileage). Thanks!

 

[Kobyoshi]

Winter Gas?
The oil industry adds a ton of "additives" to the gas during the winter months. Thus ensuring that the normal peak power gains (due to the cold dense air) and efficiency of our engines is effectively reduced.

Net result ..... they sell more gas.

/Cynical rant

 

[ZOOMit]

Do you normally fill up at the same brand of gas stations? I only fill up at Shell if i can help it. I get ALOT better mileage using their gas.

 

[Igve2shtz]

Colder weather uses more gas, so it may be a weather thing.

Also, are your two driving styles the same?

Just suggestions to consider.

 

[Falconx84]

basic tuneup - spark plugs (maybe wires), injector cleaner, air filter, fuel filter, quality oil/filter change (read synthetic).... just the easy simple stuff, anything you can do to make the engine more efficient at what it does

 

[Falconx84]

also reset the ECU..... if its anything like the ms3 ECU if we put anything less than 93 in it it pulls timing and loses power.... takes a few tanks of 93 to get it back up to par

not saying it requires 93, but if the ecu got used to it, and now is used to 87, might take a few tanks for the car to forgive you


Also, I did the math for my integra on what 93 cost me versus mileage and what 87 cost vs miles and it came out to be almost the same, but a little more costly to use 93. I did get higher mileage, but at a higher cost for the gas and so pretty much cancelled out. It came out to like 1/10 of a penny to a full 1 penny more expensive for premium or something along those lines over a full tank of gas

 

[flanimal]

the octane rating shouldn't effect your gas mileage. All it is is a measurement of how much the fuel can be compressed before it detonates. You need a higher octane fuel in higher compression and turbocharged cars so the fuel doesn't detonate before the piston is in the correct position and is detonated correctly via the spark plug. If your car runs okay on 87 (see your manual*) then using 91 is a waste of money. The gas company doesn't extra-refine or add extra techron or anything special to higher octane fuels that will give you added gas mileage.

Make sure you read manufactures specifications on minimum octane requirements. Sometimes predetonation is subtle and you won't notice it until you throw a rod.

 

[redspeed]

^^^+10

 

[Falconx84]

actually... the octane rating can have a direct effect on gas mileage. Higher octane levels allow for more compression with less fuel. If you use lower octane, you have to add more fuel for the same amount of compression to avoid detonation. This was the reason my integra saw better mileage with 93. Make sense?

I don't know much about the compression on the reg 3, but maybe this has something to do with it

 

[Falconx84]

second thought..... I'm gonna pull my dog outa this fight. It can go either way depending on the engine and how its driven and what not, and I don't know enough about the reg 3, so go with tried and true methods like what I mentioned as a basic tune. So go with the basics and as far as fuel, go with w/e works best for you, just make sure its within the specs in the owners manual.

btw, more suggestions for max mpg
http://www.autobytel.com/content/sh...m/article_page_order_int/2/article_id_int/890

octane selection from Louisiana DNR
http://dnr.louisiana.gov/sec/EXECDIV/TECHASMT/ecep/trans/b/b.htm

 

[Derek88]

Do you normally fill up at the same brand of gas stations? I only fill up at Shell if i can help it. I get ALOT better mileage using their gas.

(iagree)

I get 1-2mpg better using Shell's V-power than any other brand.

 

[Pololo_MS3]

(iagree)

I get 1-2mpg better using Shell's V-power than any other brand.

+1!

I have had the same experience and I thought it was due to my recall, ECU was reset, etc...

I was filling her up with Costco gas... and the mileage took a HUGE hit (3-4 less mpg). Now I went back to Shell and so far ot looks good...

Carlos

 

[smakdown61]

actually... the octane rating can have a direct effect on gas mileage. Higher octane levels allow for more compression with less fuel. If you use lower octane, you have to add more fuel for the same amount of compression to avoid detonation. This was the reason my integra saw better mileage with 93. Make sense?

I don't know much about the compression on the reg 3, but maybe this has something to do with it

That is actually not even close to correct. Instead of giving my opinion though which of course will be refuted i'll just point everyone here:

http://www.torquecars.com/articles/fuel-octane-ratings.php

Octane has absolutely NOTHING to do with your fuel economy

 

[Falconx84]

^^^ ummm... look at my second post

I have withdrawn from this debate because I don't feel like arguing logic. Its not worth my time and effort