OK. I've been burning some oil since I bought Kitty, but the consumption rate has been slowly, but steadily going down. I do not know if the improvement is because I've driven her 19,000 miles in 10 months or because I've been putting about an ounce of MMO in each tankful of gas. "BUT", someone suggested I also put the MMO in the oil (I've used it for many years, but only in the fuel). The suggested dose was 2 oz. per cylinder, so in went a pint.

I did this in Florida the day before I left to drive back to Maryland - 725 miles. I've done this trip before, and after one stop for fuel and driving my usual Speed Limit +10 (OK,... "with" the occasional blast of fun ), I typically pull into my driveway with about 130 miles left on the Range indicator.

"This" time however, I pulled into the driveway with 250 miles left in the tank! You've got to be kidding me. Over a hundred miles extra after just driving 725? That sounds ridiculous, but I'll take it!

Could this really be due to the MMO in the oil? Now, to be honest, I've been using 10w-30 oil vs. 5w-30 to slow the oil consumption. So, of course the MMO would lower the viscosity a little, but being as my MPG didn't go "DOWN" much when I switched to the 10w, I find that reason to be improbable.

We'll see. I'll have another couple of long trips coming up in the next few months.

Anyone else experience this?

 

I was on the way to Florida last week and my range indicator kept going up and up for the first 40 miles or so. When I started out, it said that I had 257 miles to go, and after driving about 50 miles it said that I had 287 miles to go.

When I started, my average fuel use was 18.9 and it had gone up to about 19. I suspect that your meter might be off rather then the "Magic" of the Mystery Oil.

 

Agreed. I sincerely doubt that ANY oil additive would cause a dramatic mpg increase....

 

That effect is caused by the fact that the calculation is done with a rolling average of your current fuel consumption. Steady highway cruising uses less fuel, so as the numbers accumulate from highway driving, the estimated cruise range will increase.

 

I am well aware of that, I check it frequently. This is not the first time that I have driven my car for 50 miles down the highway. Previously it might stay the same for a few miles or even increase by a couple of miles, but increasing by twenty miles after driving 50 is an aberration.
Correction, I believe that it is avg mpg.

 

The way you made your original statement made it seem as if the mechanism was a mystery to you. Hence, the explanation. In any event, some future reader might find it useful.

 

No problem. What I was trying to convey was that in my case the mileage indicator was acting hinky, which I suspect may have been the cause of what scardini experienced. I thought that the wide range of difference made it clear that something was out of whack with the indicator.

 

The amount of gas I've had available for the past few days backs up that I did in fact arrive home with significantly more in the tank.

Sure, once you get off the highway the "Range" starts to fall-off quickly, but the actual fuel remaining is the telling point. Typically I have 1/4 of a tank left; this time I had a half. So I did 725 miles on a tank and a half of fuel. That's close to 500 per tank, which isn't totally unrealistic - it's the difference from previous runs that caught attention.

 

So, what do you calculate your mileage to be on this trip home, as compared to the others?

 

On my first leg I averaged 74 mph and the computer said 27.5 mpg. This "was" higher than usual. I fueled her up and my actual mpg was 26.0. I may have squeezed more fuel in than on the first leg, but my actual mpg is always about 1.0 less than what the computer says (I've kept records since I bought her).

After the second leg, which included about an hour and a half of country roads (and occasional traffic lights), I pulled into the driveway with a higher average speed (about 75 or 76), but with a staggering 28.5 mpg indicated on the computer. I don't have the "actual" mpg for that leg because I'm still driving back and forth to work on the fuel that was left.

 

If you stick to a particular measurement system, such as the trip computer zeroed at start of trip, then the *relative* difference is a good indicator of changes despite the fact that it differs from some other system of measurement.

An indicated difference of 1 mpg is not that significant ... in my mind. Someone once explained that a specific 300 mile segment of highway yielded two different readings consistently because it is downhill to the ocean and uphill coming back.

Still ... 28.5 mpg(US) is nothing to sneeze at

 

Actually, the 1 mpg difference is between the average of all the computer's mpg indications taken when I fuel up (just before I "zero" it for the next tank), and the total number of miles I've driven since I bought her divided by the total amount of fuel I've put in her over the same time. Currently, the difference between the computer's average and the "actual" calculation is exactly 1.0 (rounded to the tenth place). Over the months this difference has never been less than .9 and never more than 1.1.

In the case of this trip, uphill and downhill are irrelevant because I'm not comparing going from A to B against going from B to A, but instead, three trips of A to B. So I cover the exact same terrain at almost the exact same speed (barring a traffic jam or two). It is a good "scientific" comparison. Which makes this last trip all the more "Mysterious". 8-)