Diff viscosity,same mpg 2013 Santa Fe Sport 2.0t

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wemay

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2013 Santa Fe Sport 2.0T

Since the wife now drives this vehicle, and could care less what oil I use, I decided she would be the perfect one to conduct this rather amateur experiment. Knowing me, I would probably alter my driving habits (subconsciously of course) to champion preconceived notions of what would happen. (she was unaware of what I was doing).

First oil change - AFE 0w30 = 22.3 mpg all city / 4127 miles
Second change - Ken 5w40 = 22.5 mpg all city / 4113 miles

My conclusion? Just too many variables involved that make any lab gained mpg a wash in the real world.
What was my preconceived notion? That AFE 0w30 would have a 1mpg advantage.
 
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Although IDK the cST measurements of either oil, often the 0W30 oils are really close(higher end of the cST) to a 40 wgt in some instances. And the 40's are at their lower end of the cST measurement.

It's kind'a like some 5W20 & 5W30 that, can be very close together or close with different brand of the other. If I said that correctly!
shocked.gif


Often a larger MPG difference may come from going to a 20 wgt compared to the 40 wgt.

Others will chime in with more info!
smile.gif
 
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The mobil has an hths of 3.0, while the 5w40 has an hths of 3.7...that's a fairly largesome would even say 'massive' difference.

Hths is more related to economy than kinematic viscosity is, which is why the ILSAC 30s try to be at the light end of the range.

It's tough trying to measure something when your error bars are bigger than the anticipated chang that you are trying to measure.
 
I've used different viscosity oils in a Toyota and there has been little noticeable difference in fuel consumption. Previously used 0w30, sae 30, 5w30; currently using 15w50.

When running sae 40 in an old Chevy, the gas mileage was decent if you let it warm up before driving, otherwise it was terrible in cold weather.
 
Originally Posted By: Shannow


It's tough trying to measure something when your error bars are bigger than the anticipated chang that you are trying to measure.



This is exactly what i mean. Just too many variables.
 
I should have used German Castrol 0W30 compared to Mobil 1 0W40 of years ago as a comparison. They were talked about here at Bob's as to how close the two of them were in their measured spec. Sorry!

I don't have the comparison today ^^^ and IDK if this is still the case.
 
You might see a greater difference using an ester synthetic that is dosed with a goodly bit of Modtc but has an HTHS close to 3.0 in your florida climate rather than differing winter grades with same 100C Kv.
 
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It would seem the gains from lightweight oils are somewhat small.

No surprise really. I've always felt that the smaller the engine the better the chance to even get a detectable gain/loss...
 
Originally Posted By: Char Baby
I should have used German Castrol 0W30 compared to Mobil 1 0W40 of years ago as a comparison. They were talked about here at Bob's as to how close the two of them were in their measured spec. Sorry!

I don't have the comparison today ^^^ and IDK if this is still the case.


There's 30s and theres 30s.

ILSAC 30s head towards the minimum HTHS for better economy, ACEA 30s often come with A3/B3/B4 (or C3) which have a minimum HTHS of 3.5 for improved protection.

There's nearly nothing between an ACEA A3/B4 0W30 and a similarly specced 0W40.

OPs 30 was clearly an ILSAC "economy" lubricant (AFE being specifically for Fuel Economy)...the 5W40 is 25% thicker in the bearings and pistong ring areas.
 
Originally Posted By: Shannow
Originally Posted By: Char Baby
I should have used German Castrol 0W30 compared to Mobil 1 0W40 of years ago as a comparison. They were talked about here at Bob's as to how close the two of them were in their measured spec. Sorry!

I don't have the comparison today ^^^ and IDK if this is still the case.


There's 30s and theres 30s.

ILSAC 30s head towards the minimum HTHS for better economy, ACEA 30s often come with A3/B3/B4 (or C3) which have a minimum HTHS of 3.5 for improved protection.

There's nearly nothing between an ACEA A3/B4 0W30 and a similarly specced 0W40.

OPs 30 was clearly an ILSAC "economy" lubricant (AFE being specifically for Fuel Economy)...the 5W40 is 25% thicker in the bearings and pistong ring areas.


Makes sense.
 


I used Lubro Moly 5w40 for the life of the car until recently. You can see from the image that it was within the "margin of error" for my data between LM 5W40 and Mobil 1. Im about 50/50 city/highway driving.

Its all part of my religious OCD fuel consumption log that I keep.

Heres my graphing as well, from Feb 2013 to current. I figure, knowing how a cars fuel consumption is behaving is all the more tools to help diagnose issues.

 
The engine is still breaking in. The mileage should be better all on its own as the engines loosens up a little. 50,000 miles down the road, you might get a more accurate picture. That being said, there may be less than 1 mpg difference in any oil - but multiplied times millions of vehicles driven daily, it adds up.
 
Originally Posted By: bigt61
The engine is still breaking in. The mileage should be better all on its own as the engines loosens up a little. 50,000 miles down the road, you might get a more accurate picture. That being said, there may be less than 1 mpg difference in any oil - but multiplied times millions of vehicles driven daily, it adds up.


This wasnt taken into consideration and I should have. It's a good point.
 
Since the measurement errors work in both directions, I would expect them to wash out over four thousand miles.
There are variables, of course.
Fuel dispensers are not completely accurate, for example, and different fuels may give different results.
This is also an engine that's still breaking in, as someone noted above.
Still, if we can draw a conclusion from the OP's efforts, it's that oil viscosity has only a very small impact on fuel economy in actual use.
From M1 AFE to a Euro-spec 5W-40 is a pretty big change to have brought no measured impact on fuel economy.
Most of us who have experimented with various grades have seen the same outcome.
 
Originally Posted By: wemay
My conclusion? Just too many variables involved that make any lab gained mpg a wash in the real world.

Exactly. As per the calculations I showed ages ago here, comparing an ILSAC rated 5w-30 to Delvac 1 ESP 5w-40, the differences were within the error bars, as Shannow noted, and one cannot tell the difference in the real world. It certainly is there, but too small for us to measure outside a more controlled environment.
 
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