Why did I pick up 1.8mpg going to a higher viscosity oil ?

[dumkid]

I change the oil every 4-5k miles. I drive the same trip every day. Live in Southern AZ. This time of year I drive with the windows open. I actually pick up about 2 mpg in the summer with the AC on. 80% of my driving is 50-60 MPH on long stretches. I get about 18 mpg on the highway 75 MPH. This is AZ it's pretty much windy all the time. I have always monitored my mpg on every tank of gas in every vehicle I've owned. If I wasn't obsessive compulsive I wouldn't be on an oil forum

But the wind mostly blows from the west, right? So you get a tailwind to help you escape California

 

[Camperguy]

Yes it does Unfortunately it's blowing a lot of Californians here with it . I'm from N.E. so I can't blame them for wanting to escape the insanity.

 

[BigCahuna]

Oh, so you guys are saying that by him running 5 tanks of gas thru the car, and upping the grade of oil he use's, and the company that made the vehicle installed a piece of equipment designed to read out the amount of fuel he used is wrong?. And none of what he's done can account accurately for the small increase in mileage ?. He might have changed out a dirty air filter, got out of the brick delivery business, maybe his wife lost weight, filled he's tires up, or he only drives with the wind at his back. He gained some mpg and he's happy, why mileage shame him for his small victory?..,,,

 

[kschachn]

Oh, so you guys are saying that by him running 5 tanks of gas thru the car, and upping the grade of oil he use's, and the company that made the vehicle installed a piece of equipment designed to read out the amount of fuel he used is wrong?. And none of what he's done can account accurately for the small increase in mileage ?. He might have changed out a dirty air filter, got out of the brick delivery business, maybe his wife lost weight, filled he's tires up, or he only drives with the wind at his back. He gained some mpg and he's happy, why mileage shame him for his small victory?..,,,

I’m not sure who is doing any of that.

 

[John105]

Short answer: You didn't.

How reliable and valid are the data….off the bat how likely are the driving conditions identical

 

[kschachn]

How reliable and valid are the data….off the bat how likely are the driving conditions identical

Impossible. Even more so if there are 5 tanks of gas involved.

 

[TiGeo]

Oh, so you guys are saying that by him running 5 tanks of gas thru the car, and upping the grade of oil he use's, and the company that made the vehicle installed a piece of equipment designed to read out the amount of fuel he used is wrong?. And none of what he's done can account accurately for the small increase in mileage ?. He might have changed out a dirty air filter, got out of the brick delivery business, maybe his wife lost weight, filled he's tires up, or he only drives with the wind at his back. He gained some mpg and he's happy, why mileage shame him for his small victory?..,,,

Hand calc'd tanks, not screen readout, you'd need quite a bit of data before/after to smooth our normal mpg noise and be able to see, statistically, if here was a change. For example, here's 2 years of data using Fuely on my Sportwagen with a trend line...so in this noise, I fail to see how changing oil viscosity could be meaningful with all the variables invoved:

 

[kschachn]

Hand calc'd tanks, not screen readout, you'd need quite a bit of data before/after to smooth our normal mpg noise and be able to see, statistically, if here was a change. For example, here's 2 years of data using Fuely on my Sportwagen with a trend line...so in this noise, I fail to see how changing oil viscosity could be meaningful with all the variables invoved:

View attachment 207251

Good observation.

I once linked an article that described the difficulty in determining a repeatable value for "real world" fuel economy. It went into many things including the necessity of using a fixed test track and only a single driver within a short time frame on the same day. But a huge variable they noted was the variability in gasoline energy content. They observed up to a 4% variance even when the fuel was purchased at the same gas station, and this was in addition to any summer/winter blend changeover. The article noted that any hope of an accurate measurement requires the use of standardized test fuel, and without that any values they obtained were not comparable.

It was also a good example of when increasing sample size (5 tanks) doesn't result in a more reliable measurement. Sometimes depending on what you're actually testing, an increased sample size results in less reliable results. In this case you're actually increasing the variability of the test.

 

[Camperguy]

I'll let you know if anything changes after 5 more tanks. Not that it'll matter

 

[nate379]

Summer blend gasolines are now being dispensed.

Not sure for gas here. I know on the diesel I just run #1 year round. Not worth fussing with #2 for a few months and ending up with stuff gelling up.

 

[Camperguy]

Hand calc'd tanks, not screen readout, you'd need quite a bit of data before/after to smooth our normal mpg noise and be able to see, statistically, if here was a change. For example, here's 2 years of data using Fuely on my Sportwagen with a trend line...so in this noise, I fail to see how changing oil viscosity could be meaningful with all the variables invoved:

View attachment 207251

That's an impressive chart! All I do is reset my mpg indicator every fill up. Like I said I do the same 120 mile loop every day. I fill up at the same gas station.When I do city driving, driving up into the mountains, off road it's obviously going to be different. If we're getting into minutia I did go from my usual Mobil 1 filter to a Purolator Boss. I've always run Mobil filters. Air filter is the same for the last 10k miles. I didn't say it was a scientific experiment, I just honestly thought it would go down 1-2 mpg from all the info I've been reading on this site.

 

[Camperguy]

Not sure for gas here. I know on the diesel I just run #1 year round. Not worth fussing with #2 for a few months and ending up with stuff gelling up.

Also didn't know Southern Arizona had winter blend gas. I never need to warm up the Jeep in the morning it's in a garage attached to the house which is usually 60-85 degrees.

 

[nate379]

Usually roufhly September to May is winter fuel here.

It's still well below freezing in much of the state. -30* right now at work.

 

[Camperguy]

I use cruise control set the same every day.

 

[Camperguy]

-30...

You can have that. Don't miss the cold, though the snow was my favorite wheeling weather. We get a decent amount of snow up in the mountains around here so I try to take a couple trips up there in the winter.

 

[TiGeo]

Good observation.

I once linked an article that described the difficulty in determining a repeatable value for "real world" fuel economy. It went into many things including the necessity of using a fixed test track and only a single driver within a short time frame on the same day. But a huge variable they noted was the variability in gasoline energy content. They observed up to a 4% variance even when the fuel was purchased at the same gas station, and this was in addition to any summer/winter blend changeover. The article noted that any hope of an accurate measurement requires the use of standardized test fuel, and without that any values they obtained were not comparable.

It was also a good example of when increasing sample size (5 tanks) doesn't result in a more reliable measurement. Sometimes depending on what you're actually testing, an increased sample size results in less reliable results. In this case you're actually increasing the variability of the test.

I suppose what it shows me at least is how variable mpgs can be.

 

[Camperguy]

I suppose what it shows me at least is how variable mpgs can be.

It's true 1000 miles doesn't really prove anything but I was happy it didn't go down...so far.

 

[ATex7239]

It's true 1000 miles doesn't really prove anything but I was happy it didn't go down...so far.

Nope. It is all on your head. So saith the Bobs.

 

[Camperguy]

Well my head and my dash board

 

[himemsys]

My driving pattern is very consistent and my driving style is very consistent. I take the same path to and from work and rarely drive the car outside of this pattern. Here is my gas mileage per tank for the past year, with an average of 31.1 MPG:
29.2
30.1
33.3
33.7
32.4
30.4
32.8
31.1
30.9
33.1
30.6
30.9
30.4
31.6
33.5
30.3
31.6
32.7
30.1
32.2
30.3
30.3
26.5
29.8
31.2
30.7

The occasional increases into the 33s are due to slight deviations with more highway miles, or warmer, less windy weather. The dips below 30 MPG are during a cold spell from mid-January to early-February when temps approached 0. The one at 26.5 in particular, I remember having to idle my car for a long time a few mornings due to severe ice on the windshields.

Car is an '03 Civic 5MT that averages about 150 miles per week. MPG calculated at the pump with each fill-up. As you can see, there is no way a 1.8 MPG change would even register as a noticeable change in my data.

IMO you'd need a controlled environment such as having a computer drive the car on a dyno in an enclosed, temperature-controlled building with the same batch of fuel, in order to get meaningful differences.