Mileage Question

[Mark71]

When will my new truck start to get better fuel mileage? I have 480 miles on it.

 

 

Thanks,

Mark

[fbachman]

when ya stop driving it....

[fbachman]

sorry, couldn't resist....

 

I would think after break-in plus anohter couple thousand miles.

 

Probably around 3000. I don't know what you're getting now, but it ain't gonna change THAT much after break in. you might get an additional 0.5-1 mpg tops.

[D&SYukonDenali]

Actually, around 5000 miles I saw a 3-4 mpg increase on my 6.2. But that is also just coming out of the winter months.

[fbachman]

Actually, around 5000 miles I saw a 3-4 mpg increase on my 6.2. But that is also just coming out of the winter months.

 

Yeah.... good 'ol winter gas. I average 15 in the summer, 12-13 in the winter when it's REAL cold, especially if I have to run in 4x4 in the snow.

 

So the winter is worth around 2 mpgs, and break in was 1-2mpgs. Makes sense.

[D&SYukonDenali]

Never get what people mean when they say "winter gas"? Is that just ethanol being added? If so, here in southeastern WI, we have that year round.

[fbachman]

Never get what people mean when they say "winter gas"? Is that just ethanol being added? If so, here in southeastern WI, we have that year round.

 

Due to EPA requirements (and other issues), there are MANY different blends of gasoline for different states, and for different seasons of the year as well. As a matter of fact, many folks would be surprised at the number of different formulations sold throughout the country. I do not know the number off hand, but it is deceptively high. Some refer to these blends as the "boutique" gasoline blends.

 

In fact, right after Katrina, one of the first things Bush did was to suspend the "boutique gasoline" requirements, temporarily, allowing any blend to be sold anywhere--- in an attempt to provide relief for the remaining refineries that were operating to produce more gas than they normally could without all of the special, regional, recipies.

 

The additive properties of the gasoline blends in the winter are detrimental to fuel economy, but good (SUPPOSEDLY) for emmissions, as particulate emmissions react differently in the atmosphere in cold vs. hot temperatures. Thus, different additives are added in the winter to reduce emmissions. Furthermore, the shelf life of gasolines have decreased over the years, and the shelf life is highly dependent on ambient temperatures. Thus, there are different additive groups used to control shelf life as the seasons cycle as well.

 

The additives I am referring to are chemical additives, not necessarily alcohol additives.

 

Of course, there is a fundamental physics thing going on in the winter as well. In cold ambient conditons, the air density is higher. As an (normally aspirated) engine's cylinder draws in a constant VOLUME of air for each intake stroke, this volume of higher density air thus ontains more MASS in the cold seasons. Thus, to maintain a consistent fuel-air-ratio, the engine control has to deliver more fuel to maintain the correct/ideal fuel air ratio. Thus, in the winter, "by design", you'll need more fuel to run the engine. Thus, the slight hit in fuel economy in the cold, versus the hot seasons.

 

Hope this helps.

[Griffin86]

You also idle more in the winter.

[Silverado4x4]

You also idle more in the winter.

Yes thats a very good point with idle time also the fluids are thicker in the winter making the truck work just a little harder to move things.

 

When I went to Tennesse a few weeks ago and some people may call me a liar but I have 4000 miles on the truck now and got 22 mpg on the highway hand calculated but I also ran the speed limit all the way down at 65, somethimes I ran 70 but I didnt push the truck hard at all.

[fbachman]

You also idle more in the winter.

Yes thats a very good point with idle time also the fluids are thicker in the winter making the truck work just a little harder to move things.

 

When I went to Tennesse a few weeks ago and some people may call me a liar but I have 4000 miles on the truck now and got 22 mpg on the highway hand calculated but I also ran the speed limit all the way down at 65, somethimes I ran 70 but I didnt push the truck hard at all.

 

 

I wouldn't call you a liar at all...

 

I also recently travelled from Ohio to TN, and running 79mph according to TomTom, I got a hand-calculated 19mpg, which I fully believed could have easily been pushed to the low 20s if I stubbornly ran 65mph.....

 

[99silverado1500]

It took our Sierra LBZ Dmax about 10K miles to get to be extremely powerful and getting 15+ mpg. Our old sierra 5.3 took about 7000 miles until it got its peak MPG.