Increased MPG with 5-20

[tig1]

Just returned from a trip to Florida and my MPG has increased under the same conditions as my last trip in November. Same wt.,speed, weather about the same except I had a stong head wind for the first 300 miles coming back on this trip. The increase was 1.1MPG with the 5-20 versus 5-30 in Nov. I set the on board calculator as soon as I hit the interstate close to home and checked it at the exit in Gainsville. Reversed that coming home. This was the Fusion.

 

[Bill in Utah]

What was the actual miles vs gallons used worked out on paper?

Both trips. I'm not a fan of the on board stuff. Not very accurate most of the time.

 

[beast3300]

So was the fuel economy figured out by hand or just the onboard thing?

 

[Ravi08Mustang]

My 2008 Mustang GT's onboard MPG calculator is always 1 to 1.5 MPG better than my actual MPG when calculated by hand. Can't rely on it.

 

[tig1]

Originally Posted By: Bill in Utah
What was the actual miles vs gallons used worked out on paper?

Both trips. I'm not a fan of the on board stuff. Not very accurate most of the time.


This was the on board monitor. I have checked the mileage with this car several times by hand and it is always very close. Usually .2 to.5 MPG less than the monotor.
My on board monitor showed 32.8 this trip vs 31.7 in Nov. I set the cruse on 2500 RPM(72 MPH) on both trips. No AC used either time.

 

[beast3300]

That's a pretty good gain.

 

[JAG]

A factor to consider: gasoline's energy content varies by what month it is - warmer months have higher energy. I hope the viscosity change does give you better fuel economy.

 

[Jim 5]

Originally Posted By: JAG
A factor to consider: gasoline's energy content varies by what month it is - warmer months have higher energy. I hope the viscosity change does give you better fuel economy.


I agree. On the other hand, the manufacturers wouldn't have mandated a wholesale change from 5w30 to 5w-20 if there wasn't a fuel economy pay-off.

Also the on board computer no matter how inaccurate it might be, will be as against itself, uniformly accurate or inaccurate as the case may be. My view is that it may not be an accurate way to measure exact MPG's, but it will be accurate in measuring the delta between trips the way tig has used it, from the same on board computer (assuming other factors causing a spurious correlation can be eliminated).

 

[rclint]

A change in tires, air pressure in tires, weight in car (luggage) anything can effect the mileage. I also am very skeptical of economy gains from a 5w-20 oil when coming down from the same brand ( Mobil 1) 5w30. I'm also glad the new on board computers are much more accurate with mileage, I have never had one anywhere close to correct actual fuel mileage. By the way I'm new sure how much the wear on your tires if they were the same tires changing the total diameter would impact your actual fuel mileage... I would assume it would be close if not greater than going from a 5w30 to a 5w-20. Another biggy is the accuracy of the tank, temperature when filled, how soon you called it filled so many variables we have to figure in when contemplating fuel economy !!

I do hope it was the oil, however in all my years of driving, oil changing, trying different oils, weights etc I have never found an oil to consecutively improve my fuel economy enough to show it on paper when calculated by hand... for 3 tanks, my mileage is also always up, and down from tank to tank

On edit- even down to if you used the defroster or not, rear drains alternator, front turns on a/c

 

[FZ1]

I believe it.

 

[Bumpside 427]

Originally Posted By: FZ1
I believe it.


I put in new RP 5w20, air filter, run my tires on the high side, and put in new Bosch Platinum/Iridium plugs.
I get 20 miles more a tank. It's a 14 gallon tank, and I get 24MPG average.
So, it was almost like an extra gallon per tankful.
I measure every tank, so it's not just a glance at the ODO.

 

[Ben99GT]

Originally Posted By: Jim 5
Originally Posted By: JAG
A factor to consider: gasoline's energy content varies by what month it is - warmer months have higher energy. I hope the viscosity change does give you better fuel economy.


I agree. On the other hand, the manufacturers wouldn't have mandated a wholesale change from 5w30 to 5w-20 if there wasn't a fuel economy pay-off.


It supposed to be within a 1/2 of a percent difference though. I've seen different oils effect gas mileage by about 1 mpg though, so I can believe it.

 

[HTSS_TR]

My experiences with MPG increase with thinner oil is similar with Tig1 experience. I went to Vegas almost every summer for more than 20 years, the last 10 years with E430. The previous 8 years with M1 0W40 in the engine the gas mileage were between 23.5 and 24.5 MPG, summer 2008 I had PP 5W20 and MPG increased to 26.0 MPG. All the times I was cruising at around 85-90 MPH or faster. Another I observed: coolant temperature was about 3-5 degrees C lower with thinner oil.

 

[bradepb]

In 2001 when ford went to 5-20 they stated it increased there average by .6 mpg across the fleet. so in some cars it makes more difference and some less, my mpg in my escape is about .9 better close as I can figure with 20vs30

 

[mechtech2]

I also believe his data is accurate.

I do not believe the increase in fuel economy is totally from the oil.

 

[Pesca]

Originally Posted By: beast3300
That's a pretty good gain.


Really?
If you move it back in liters per 100 kms, the change is only one full glass (250ml) for every 100kms done.

As others said, just tires not inflated the same or a small change in the weather can cause that.

But yes, it is always better to get a better fuel mileage than a worse one.

 

[tig1]

Originally Posted By: Pesca
Originally Posted By: beast3300
That's a pretty good gain.


Really?
If you move it back in liters per 100 kms, the change is only one full glass (250ml) for every 100kms done.

As others said, just tires not inflated the same or a small change in the weather can cause that.

But yes, it is always better to get a better fuel mileage than a worse one.


My gain was 3% which is pretty good for just using a differant wt. oil. Also I am careful with tire pressure. I carry 34 PSI and check it often.

 

[Jim Allen]

The onboard monitors may not reflect an accurate MPG, but they can reflect an accurate change.