Surprising increase in truck MPG

I have a Chevy Silverado pickup that is by now about 18 months old.

I was never able to get more that about 220 miles out of a 22 gallon tank of gas, sometimes even less.

However, the last three refills, gave me 280, 266, and 283 miles per refill. (I usually run until my tanks gets fully empty, since I have an emergency gas canister for the instance when I run out of gas).

This represents approximately 22% increase in MPG that I have hard times explaining. I see three possible explanations.

1) Just before those refills, I did an oil change and used Mobil 1 synthetic oil. The previous oil changes were at a service station.

2) The engine had a chance to "burn in" and naturally improved its efficiency

3) something is seriously mistaken in my measurements.

I am at a loss and am very puzzled. Can synthetic oil really account for that much of an increase? I highly doubt it.

i
Reply to
Ignoramus15242
Loading thread data ...

Mobil itself claims only a 2% improvement in fuel economy, with comparable oil weight. My experience is somewhat better, but, like you, I can't really account for break-in and so on.

I use Mobil 1 5W-20 in my Ford Focus, and I intend to stick with it.

-- Ed Huntress

Reply to
Ed Huntress

For the next oil change, I may use regular cheap oil to see if there is any difference.

i
Reply to
Ignoramus15242

Has the mix between Highway and City driving changed much?

You might also not want to run your tank down so far. Electric fuel pumps that are in the tank last a lot longer if you keep them well submerged. Just a thought.

Reply to
John R. Carroll

RCM only

On Fri, 18 Apr 2008 10:21:25 -0500, with neither quill nor qualm, Ignoramus15242 quickly quoth:

I am told (by friends who buy new vehicles often) that there is no longer any break-in period necessary. One says that precision CNC machining precludes that nowadays. Toyota asks that we vary our speed during the first 1,000 miles, but that's it.

Are you using the same pump at the same station all the time? By law, all filling station slabs have to be level, but "settling of contents may occur during shipment."

Are you filling the tank or is a gas jockey doing it? Some allow the tank to top itself, others pump in as much as they can possibly get. The extra pumping might be your difference in at least one of those calculations.

I need to put the fourth tankful in my new Tundra today and am thinking about having that first oil change with a synthetic oil to see if it makes any difference for me.

The wrong oil in really cold weather can make a difference, but this is springtime. I doubt it, too.

-- The only difference between a rut and a grave...is in their dimensions. -- Ellen Glasglow

Reply to
Larry Jaques

There you go.

You have to use 'miles' to find 'miles per gallon', not the fuel gauge. Voltage differences, temperature, the tilt of the road and lots of other things make the fuel gauge nothing anyone should think of as 'accurate'.

You check the odometer when you fill up. On your next fill, no matter if even a half a tank, you check the miles on the odometer again. This gives you the number of miles traveled and the amount of gas used to do so. Then you just divide the miles by how many gallons used.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 'New' frame in the works for '08. Some Canadian Bush Trip and Build Photos:
formatting link
Reply to
Mike Romain

Mike, the gallons used number was rather consistent.

Otherwise your idea is very good.

i

Reply to
Ignoramus15242

There's no break-in necessary to protect bearings, rings, etc. But there still is a reduction in friction as the engine breaks in.

Reply to
Ed Huntress

I'm going to take a wild guess - that traffic is running a bit slower.

Richard

Reply to
cavelamb himself

traffic congestion drives down MPG for most vehicles. It would be rather rare that it would result in a steady speed that was better for his truck.

Reply to
Brent P

Consistent enough to be off 16 miles or +/- 5%. For a fuel gauge, this is wickedly accurate or your eye on the line is.

Even a head wind vs a tail wind can account for 5% mileage difference when actually measured by the 'miles' driven.

Reply to
Mike Romain

I would recommend you do not run until the tank is completely empty. The high pressure EFI fuel pump really doesn't like that.

Reply to
Thomas Tornblom

Could be any of the three, but Mobil 1 is very good stuff. I always get receipts from every fill up and I write the current odometer reading on them so I can eventually take a stack of those receipts and punch them into my MPG spreadsheet.

Reply to
Pete C.

I never think in terms of MPG (miles per gallon), but rather in terms of GPH (gallons per hour) . At the speeds we are allowed to travel this is a better gauge of fuel/engine performance.

cheers T.Alan

Reply to
T.Alan Kraus

"T.Alan Kraus" wrote: I never think in terms of MPG (miles per gallon), but rather in terms of

^^^^^^^^^^^^^^^^^^^^^^ You will get *really good* gallons per hour standing still with the engine idling. How is that a measure of anything useful? Assuming that you need to know the gallons per hour, how do you get numbers? Do you have a flowmeter in your gas line?

Reply to
Leo Lichtman

Kinda sorta exactly.

When traffic slows down a bit and spreads out speeds tend to stabalize.

Reply to
cavelamb himself

On what planet? When traffic slows down here, it clumps and clumps grow into each other and when the clumps meet it soon becomes stop and go.

Reply to
Brent P

I'd vote for the drivetrain getting broken in, with possibly an adjustment for seasonal changes and/or fuel formulations. I regularly get 400+ miles from a tank of gas in my car in the summer, but it drops to 325-350 in the winter. I blame increased use of the A/C (for defrost) and am curious if the difference between "summer gas" and "winter gas" contributes in any way.

nate

Reply to
N8N

Live in an area in the US that uses reformulated gas for the colder months? That increase is the same you would find here in NY after they switch over to the summer blends of gas.

Reply to
Steve W.

Could be your part of the world just got the seasons 1st shipment of 'non-winter-blend' gasoline.

Or maybe they were selling gasohol (10% ethanol) and stopped.

Dave

Reply to
spamTHISbrp

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.