Surprising increase in truck MPG

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.

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

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.

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

Mike, the gallons used number was rather consistent.

Otherwise your idea is very good.

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

Richard

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.

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.

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

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.

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

"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?

Kinda sorta exactly.

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

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.

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

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.

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

Get a container rated for gasoline storage.Put one accurately measured gallon of gasoline in the container.Mount it to the fuel intake of your vehicle's engine.Miles per gallon. cuhulin

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

Also in the summer your oil viscosity will be down. I'd suspect the service station has been using a higher viscosity mineral oil. Don't think it's synthetic that makes the difference, I think its viscosity (at operating temperature). Synthetics hold their viscosity better as they warm up (which goes the "wrong" way).