Well, I've been testing all summer and here's what I have so far:




There are some notes to point out:

1. The Royal Purple was 5 weight, not 10 weight like the Mobil 1.
2. Whenever possible I tried to use the exact same gas and pump at the local QT.
3. I tried to keep my driving habits the same as much as possible. I didn't try to Hyper mile or gun it, just my usual oblivious self.
4. The lowest Mobil 1 mileage is misleading as I spent a large amount of time idling in the driveway fixing the A/C system. I did not omit it as I didn't want gaps in the mileage or other data.
5. Overall, I noticed more consistent MPG's with the Royal Purple. The engine also idles noticeably smoother, and I don't seem to burn oil with the RP. I had burned about 3/4 of a quart with the Mobil 1 after 3000 miles. I do not know what to attribute this to.
6. I did notice that my MPG's went up significantly (+0.5 mpgs) when I let the tank run down lower. My theory is that I was not lugging around as much dead gas weight and this actually help the mpg's slightly toward the end of the tank. I do have a 35 gallon tank which is a load of excess gasoline weight. I'm going try filling up half tanks later to see if that helps more.
7. All results were taken with the SCT economy tune (87 octane) provided by Hemifever. Next, I'm going to check out the 93 octane performance tune for a few thousand miles to see what my fuel economy is on that tune.

Any question feel free to post!

 

RP is really a great product.. and in my neck of the woods it only about $0.50 more per qt.

 

is that all in town?

 

it has been my
'school of hard knocks' experience
that you have to alternate every tank
from with mod to without mod
and if you don't
you are more measuring changes in
weather or gasoline blend
than the modification you are interested in

i know that sounds like a real PIA
but with a Fumoto valve on the oil pan plug hole
and two separate lube oil containers it is doable

I also found you need to alternate no less than 6 times

want to find better results quicker?

if you could enlist a friend with a similar truck
in just one long day you could do
two SAE/TMC type 4 MPG tests
that are the 'gold standard'
and have very little variation (less than 2%)

this is the way Grant on Mythbuster's TV
or Walmart's trucking fleet
or Goodyear Tire Company
or Lubrizol, the maker of Chrysler's ATF+4
would do it

http://web.archive.org/web/200511050.../new_lubes.asp

-------------
The right way to do it
Goodyear goes by the book with Fuel Max test
When Goodyear introduced its new Unisteel tires with Fuel Max technology last year, and claimed that they were more fuel-efficient than its older designs, the company invited the press to come to its San Angelo Proving Grounds in Texas and observe an SAE/TMC Type II fuel consumption test, pitting old against new.

In this case, two identical tractor-trailers — a control rig and a test rig with the same powertrain, mileage, horsepower, GCW, tires, pressure, etc. — were fitted with removable, portable fuel tanks, which were weighed before and after identical runs of at least 28 miles at the exact same highway speed. Fuel consumption was measured by tank weight, and the two rigs were compared as a baseline. Three runs, which must produce results within 2 percent of each other, were made. In this case, the two rigs’ fuel consumption figures were consistently within 1 percent of each other.

Next, the test was repeated, with the control rig unchanged, and the test truck fitted with the component to be tested — in this case, the new tires. Over the course of three runs, with results within 2 percent of each other, the test truck had consumed about 7.5 percent less fuel per run.

Claim made, point proved, case closed.
--------
first pumping out the tank,
adding back in measured gallons,
then running the MPG test,
then measuring what fuel is left,
is how Mythbuster's TV runs a perfectly good TMC/SAE test version.
There is a separate vent hose on the Dodge Ram fuel tank that can be used to do the pumping out.

don't take anything in this post as a put down
MPG tests are hard

the 18 wheel trucking industry has been lucky to have many sharp and 'real world' people working on the problem of getting reliable results

http://www.etrucker.com/apps/news/article.asp?id=60421

 

Hank, I don't take it as a put down at all. I really enjoy reading your posts, they are always thoughtful and contain a nugget or two of info that I never knew before. And you tend to back up your opinions with facts which is always quite nice.

If I were looking for a stand-up-to-all-scrutiny test than I agree that the test you posted would be ideal. This was merely a log I started earlier and promised a few members I would post up later. I'm not advocating RP or Mobil 1 as an oil of choice, just relaying info I have gathered over the last few months. I don't claim that anything I did followed the letter of the law as far as the scientific method is concerned, however I did try to limit a few variables to get results that I felt comfortable with. for me, over the time period involved and with my particular driving habits, this is the data I got. I have no idea what the degree of +/- error in my tests was, and I don't even know if I could truly extrapolate any useful data as far as MPG's are concerned from this test. I did discover that RP runs a little smoother in the engine though, and that's worth the extra few bucks every 7500K to me.

 

It's kind of mixed, you can't really get anywhere in DFW without getting on a highway. I can say that I didn't really take any trips out of the ordinary for the last few months.

 

several weeks ago I noticed that there were new Mobil One synthetic bottles in Walmart that had 2% MPG improvement guarantees on the back label for this special 0W-20 formulation

for typical 14 MPG mixed driving
this means we are looking for
a 'needle in a haystack'
or 0.28 MPG improvement

only the special conditions of a
TMC/SAE type test
will even get you to the point of being able to detect
a 2% or more gain.
The TMC/SAE guys say in their explanations
that a single test run their special way
can only find improvements that EXCEED 2%

in other words
if the change is between
minus 0.28 MPG
and
plus 0.28 MPG
their test is not able to dependably detect it

you can get around this by running their test
four times or more
which would improve detection to 1%

the same kind of thing would apply to finding
the small MPG benefit
of that 'tailgate thingie'
during 70 mph highway driving

 

I've seen the green bottle of Mobil 1 at Walmart that supposedly raises MPG's but it was simply rebranded 0W30 oil.

 

Mobil 1 EP can withstand much longer extended drains then royal purple though. According to most all independent lab results, from forums like BITOG where people are totally nuts for motor oil, mobil 1 EP can usually go 15k-20k miles before it really needs to be changed. I don't think royal purple even comes close. I think it has to do with Mobil 1 being a true PAO synthetic with a decent ammount of ZDDP to withstand such long durations.

If you calculate that in, and say you cahnge your oil once a year on mobil 1, like I do, then you save on oil that way too! Just $25 a year for 5 quarts and a filter. That will offset .5 mpg easy.

 

+1 on what MonkeyWrench4000
says above,
especially the part about joining other volunteers
on the lube oil discussion websites
and doing your own oil analysis tests
as part of an internet connected group
all trying to improve knowledge
and decrease BS