Best Gas Mileage OIl

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I have my own ideas about motor oil and MPG which are based on time-honored math calculations and backed-up with an aftermarket digital monitor (to check the math). But I wanted to hear what others have found to be true in real-world testing. I am asking what Oil gives you the best gas mileage and how you know this to be true.

I am assuming that a Synthetic Oil offers less resistance, but I could be wrong. I used to use Exxon Superflo back in the 90's (that's 1990s for you comics). Because after exhaustive testing between Castrol, Pennzoil, then Superflo, I learned which offered less engine resistance thus the best gas mileage. I used a sales route that I ran every week and ran a few tanks through each oil change. The route never changed and since it was rural I used cruise control. Not terribly scientific, but close enough to develop a discernable pattern. The Superflo won handily.

As they say, your mileage may vary, but what is your experience?
 
I doubt you will notice much difference from one to the other. I've known people to run 20w50 and not notice any real changes.

Oils affect will be so much smaller compared to tire type, air pressure, engine upkeep, and most important driving habits.
 
Originally Posted by cwhard
I have my own ideas about motor oil and MPG which are based on time-honored math calculations and backed-up with an aftermarket digital monitor (to check the math). But I wanted to hear what others have found to be true in real-world testing. I am asking what Oil gives you the best gas mileage and how you know this to be true.

I am assuming that a Synthetic Oil offers less resistance, but I could be wrong. I used to use Exxon Superflo back in the 90's (that's 1990s for you comics). Because after exhaustive testing between Castrol, Pennzoil, then Superflo, I learned which offered less engine resistance thus the best gas mileage. I used a sales route that I ran every week and ran a few tanks through each oil change. The route never changed and since it was rural I used cruise control. Not terribly scientific, but close enough to develop a discernable pattern. The Superflo won handily.

As they say, your mileage may vary, but what is your experience?

How about if you share your data to help start the conversation?
 
True enough that the less friction on internal engine parts the better the efficiency of the engine. Back in the day Arco tried graphite and it failed due to it clogging up passages and caused engine failure. I suppose now I would look for high Moly content. I'm sure there are other factors, mainly viscosity. Using the lowest viscosity oil that doesn't lead to engine damage would probably be the easiest way. 0W16 is all about the economy.
 
I've only used conventional oil for one OCI in my Ranger. It's been synthetic for 40 years. The difference between conv and syn was marginal but the syn won. I'm having very good reports with the ST I'm using now. Better than the previous runs of M1. I've always thought syn would give better MPG. It may be marginal but every little thing you do helps and the cost isn't much different.
 
The only way to know the real friction differences would be on a engine dyno for long runs. It would be the only way to keep the variables the same. Your test is a good thought but has no verifiable results that could be replicated
 
It will make little difference.. In most engines, if you went from 0w-20 (which, by nature must be synthetic) to a 5w-30, you might see a small drop in MPG.. perhaps 1-5% difference.. but you would have a hard time actually measuring it. On the other hand, if you went from a full-synthetic 5w-30 to a conventional 5w-30, you would almost certainly get the exact same MPG.

This also assumes that ALL other factors are exactly the same, of course.

Just changing tire pressure by 4 or 5 PSI could result in the same 1-5% change in MPG. Heck, a change in ambient temperature of 10 degrees can even change your MPG by a couple percent.
 
Back in '04 I switched from conventional to synthetic of the same viscosity, as I had a 120 mile round trip once a week.

Driving the same highways at the same speeds, the synthetic gave better mpg and ran cooler.

YMMV
 
Use synthetic because it sludges less, has better flow properties at low temperatures and lasts longer, creating less waste oil. With modern oils you won't see a noticeable difference between synthetic and conventional at the same viscosity - it only matters at the fleet level.
 
Viscosity is viscosity.

I ran spin loss tests with really good Himmelstein torquemeters comparing syn and petro based transmission fluids and "surprise" they were the same if they had the same viscosity.

Remember that the mpg improvement claims of the early Mobil 1 advertising were based on going to 20wt when almost no OEM was speccing that.
 
During the short OCI (1000mi) I averaged 17.8 MPG according to the dash on Formula Shell Conventional 5w20 and a Carquest Red.

2500mi on the current fill, Schaeffers 5w20 and a Mahle I'm averaging 21.6 MPG

I always leave "Trip B" alone during a OCI to monitor my engine run time on the fill as well as the MPG for the entire fill.

Many factors do play into MPGs as well, probably moreso than oil choice.

Ambient temps, tire pressure, tire brand/model, fuel choice, driving conditions in general, etc. All play a factor. Idk if it was the changing of the oils, or maybe the switch from the previous truck owners Primewell tires (yuck) to the BF Goodrich Rugged Terrain T/A tires I have now, or other factors.

I use 89 octane and Sunoco usually.

Edit: you were the same one who posted the Amsoil post. I'm sure somewhere on their site they have some random graph that says you'll experience a minimal increase in MPGs using their oil, as most if not all oil companies do.
 
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I would say redline oil but it's too thick by hths standards. I would look to a really basic oil like a Grp3 0w20 or whatever your can recommends.
 
Originally Posted by sloinker
... Back in the day Arco tried graphite and it failed due to it clogging up passages and caused engine failure. ...
That never happened or even threatened to happen when I used it for near 100k continuously.
 
Aside from what ARB1977 said, the only other difference will be the lowest HTHS oil that still meets the requirements of your engine, and you'll never be able to calculate the difference in the real world.
 
There is no BEST oil for MPG
Impossible to repeat and duplicate every single event during the course of a trial run on each brand tried on the street.
Can't do it
Bolt an engine to a dyno in a controlled room
And MAYBE just maybe one brand over another will tweak out a small gain
 
If every factor except oil was held constant, then 0W-8 oil would give better gas mileage. That's the whole drive of thinner oils - ie, less shear friction.

As far as oil formulation in the sane viscosities from the major oil blenders, I highly doubt you could measure much if any difference if all other factors were held constant. The viscosity has a stronger influence on engine drag then the oil formulation.
 
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