Can your oil selection really affect your mpg?
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I believe it has more to do with the low speed torque output of the engine apples to apples now that only rotary type compressors are used.quote:
Originally posted by Ugly3:
javacontour - Nor is the Vette the same interior volume to cool.
Just goes to show you how stupid some people can be. I have wondered why my A/C is so much more ineffieicent than other units. Never thought about the volume being cooled. Great thought Java, thanks!
A V-8 will make more obviously but so will the 2.7 4 cyl Toyota with the dumb round cam lobes and how they are phased vs a 1.6 that makes peak torque higher much in the RPM range with a not so flat curve compared to the 2.7 .
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I think Motorbike has the correct view. The amount that AC impacts your mpg is the same as how oil can as well. If you've got an engine that inherently consumes a substantial amount of fuel just off idle (like a V8) ..I think that the impact of any drag is next to nothing in comparison to "operational variables". If on the other hand you've got some powerplant that has barely enough power to idle and developed all its power in the upper rpm ranges (smaller engines) ..I believe that they would evidence any fractional hp taxation (ac, oil visc).
But I also don't think it's just that simple. In the mpg meter in the aforementioned Town & Country ..you've got a large cabin to cool. So ..perhaps the duty cycle time on a much smaller cabin would have virtually no impact on mpg. On the other hand a T&C has a relatively heavy aerodynamic drap coefficient compared to something else ..so that it might not be impacted as much by having the windows open compared to something that can be highly effected by the entrapment of outside turbulance.
I would say that typically the impact of a given oil viscosity is comensurate with it's placement in the fractional hp taxation heirarchy. Same thing for ac. Both would vary depending on your typical use.
But I also don't think it's just that simple. In the mpg meter in the aforementioned Town & Country ..you've got a large cabin to cool. So ..perhaps the duty cycle time on a much smaller cabin would have virtually no impact on mpg. On the other hand a T&C has a relatively heavy aerodynamic drap coefficient compared to something else ..so that it might not be impacted as much by having the windows open compared to something that can be highly effected by the entrapment of outside turbulance.
I would say that typically the impact of a given oil viscosity is comensurate with it's placement in the fractional hp taxation heirarchy. Same thing for ac. Both would vary depending on your typical use.
2mpg isn't insignificant. I'd love to get an addtional 2mpg!
"Can the oil selection really affect your mpg?"
I doubt it. Some posters on BITOG have stated that going from Brand X 15W-40 synthetic to Brand X 5W-30 synthetic may have saved 3.4% in one test. That's a pretty close call and a leap to think that would be a consistent finding over time for everyone. And that was with a significant difference in oil visc.
Isn't the difference between an API "fuel efficient" motor oil and one not so designated just a fraction of a percent? Too many variables to ever know, especially with the use of ethanol blends in the gas, which significantly decreases mileage. Pumping up the tires may have more effect, at least that is my experience.
I doubt it. Some posters on BITOG have stated that going from Brand X 15W-40 synthetic to Brand X 5W-30 synthetic may have saved 3.4% in one test. That's a pretty close call and a leap to think that would be a consistent finding over time for everyone. And that was with a significant difference in oil visc.
Isn't the difference between an API "fuel efficient" motor oil and one not so designated just a fraction of a percent? Too many variables to ever know, especially with the use of ethanol blends in the gas, which significantly decreases mileage. Pumping up the tires may have more effect, at least that is my experience.
"Can the oil selection really affect your mpg?"
Of course it can/does. The smaller the engine the bigger the difference. I have seen it time after time first hand.
Why anyone would believe otherwise is beyond me. You not only can see the difference in MPG, but you can feel it in how the engine revs and accelerates. You put a heavy 30 weight or a 40 weight in a 4 banger that calls for 20 weight or even 30 weight..there is a difference.
Of course it can/does. The smaller the engine the bigger the difference. I have seen it time after time first hand.
Why anyone would believe otherwise is beyond me. You not only can see the difference in MPG, but you can feel it in how the engine revs and accelerates. You put a heavy 30 weight or a 40 weight in a 4 banger that calls for 20 weight or even 30 weight..there is a difference.
My $0.02 worth...
Winter-formulated gas stinks! The supposed benefit of "less emissions" (Sorry: it just didn't seem to turn out that way) results in appreciably reduced miles per gallon, leading to (you guessed it!) more consumption!
Here in wack-o O-re-gun they are finally going to suspend the mandatory reformulation.
It didn't work. Oh, well... What will we regulate next?
Sure, oils can reduce or extend mileage. The real question is... HOW MUCH?
IMHO, driving style, tire air pressure, etc. have bigger effects than oil weight. Obviously the state of tune, speeds, a/c usage, acceleration have more direct and more noticeable effects than oil selection in most cases.
Cheers!
Winter-formulated gas stinks! The supposed benefit of "less emissions" (Sorry: it just didn't seem to turn out that way) results in appreciably reduced miles per gallon, leading to (you guessed it!) more consumption!
Here in wack-o O-re-gun they are finally going to suspend the mandatory reformulation.
It didn't work. Oh, well... What will we regulate next?
Sure, oils can reduce or extend mileage. The real question is... HOW MUCH?
IMHO, driving style, tire air pressure, etc. have bigger effects than oil weight. Obviously the state of tune, speeds, a/c usage, acceleration have more direct and more noticeable effects than oil selection in most cases.
Cheers!
Tenderloin has it right.
My Nissan 4-banger pickup dropped 2 mpg on the highway when I switched from 10W-30 to 5W-40.
My nephew's 4.0L Jeep didn't so much as blink when switched to a 40 wt.
My Nissan 4-banger pickup dropped 2 mpg on the highway when I switched from 10W-30 to 5W-40.
My nephew's 4.0L Jeep didn't so much as blink when switched to a 40 wt.
A thinner oil will give better mileage ... how much better mleage you get will depend largely on how much you belive in thinner oil being the Holy Grail.
I was thinking more in the terms of dino vs synthetic at the same weight(s).
Okay, the winter formulation gas we get, with more ethanol, thats for reduced emissions right??
But we have more of them, as most every car gets worse mpgs???
There's a government program for ya....
Smith
But we have more of them, as most every car gets worse mpgs???
There's a government program for ya....
Smith
I just switched my Festiva from M1 0w-30 to Havoline 10w-30 feel a difference but better gas mileage, dropped with each step Castrol 10w-30, M1 10w-30, M1 5w-30, M1 0w-30. My 5.4 F150 M1 5w-30 16-17mpg, MC 5w-30 14-15mpg and Havoline 5w-20 TBD but should be 16-17 by eyeing the gas gauge drop. All depends on the design of the engine. Eric
The more heavily loaded the engine is, as a % of maximum power, the less effect oil thickness should have on fuel economy. An engine running with no load at high RPM should show the biggest difference, since lots of the energy just goes to friction, with a small amount to pumping losses. The more load, the less it matters.
A thinner oil will always result in higher fuel efficiency except:
1) When the rings and cylinders are worn - in this case the heavier oil gives you better compression.
2) If the oil is so thin you are functioning under conditions of "boundary" or "mixed mode",lubrication conditions too often throughout the engine. In this case, friction losses ramp up rapidly, often followed quickly by part failure.
As a general rule, every SAE grade you go down in viscosity will yield an additional 1%-2% in fuel efficiency. Every 5 pts you go down the the "W" number will yield an additional 0.5% in fuel efficiency within the same SAE grade. So for example, the difference between an SAE 0w-30 and SAE 5w-40 is on the order of 1.5%-2.5% in fuel efficiency.
The effectiveness of specific types of organic friction modifiers (esters, moly, boron, etc) can also influence fuel efficiency. You'll only find this out by field testing various formulations.
Tooslick
1) When the rings and cylinders are worn - in this case the heavier oil gives you better compression.
2) If the oil is so thin you are functioning under conditions of "boundary" or "mixed mode",lubrication conditions too often throughout the engine. In this case, friction losses ramp up rapidly, often followed quickly by part failure.
As a general rule, every SAE grade you go down in viscosity will yield an additional 1%-2% in fuel efficiency. Every 5 pts you go down the the "W" number will yield an additional 0.5% in fuel efficiency within the same SAE grade. So for example, the difference between an SAE 0w-30 and SAE 5w-40 is on the order of 1.5%-2.5% in fuel efficiency.
The effectiveness of specific types of organic friction modifiers (esters, moly, boron, etc) can also influence fuel efficiency. You'll only find this out by field testing various formulations.
Tooslick
Too Slick summed it up well.
I have seen cars (my own! - 5+ years back) with the FULL synthetic treatment: oil, trannies, diffs and greases - done all at once - gain about 3mpg.
It wasn't just a blip. The MPG went up and stayed up......
Side note: I nominate Norm Olt for post of the year!!!
I have seen cars (my own! - 5+ years back) with the FULL synthetic treatment: oil, trannies, diffs and greases - done all at once - gain about 3mpg.
It wasn't just a blip. The MPG went up and stayed up......
Side note: I nominate Norm Olt for post of the year!!!
Even though many claim the 1-2% per SAE grade and .5% for ever 5 increment drop on the W side I have never seen it happen in real life. I guess my driveing style and those factors outside of my conrol must eat up the 1-2% improvement! Do not get me wrong it makes perfect sense I just have never seen it happen in real life. I do not even know anyone other then fellow bitog members that have ever seen it hapen!
Could not agree more, oil is low on the list of economy improvers.quote:
Originally posted by Norm Olt:
My $0.02 worth...
Winter-formulated gas stinks! The supposed benefit of "less emissions" (Sorry: it just didn't seem to turn out that way) results in appreciably reduced miles per gallon, leading to (you guessed it!) more consumption!
Here in wack-o O-re-gun they are finally going to suspend the mandatory reformulation.
It didn't work. Oh, well... What will we regulate next?
Sure, oils can reduce or extend mileage. The real question is... HOW MUCH?
IMHO, driving style, tire air pressure, etc. have bigger effects than oil weight. Obviously the state of tune, speeds, a/c usage, acceleration have more direct and more noticeable effects than oil selection in most cases.
Cheers!
I agree. The more scientific way to do this is to keep a running average over the most recent 5 tanks. That dampens out small variations such as the tank not being equally filled each time.
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