MOBIL 1 0w20 vs AMAZON BASICS 5w20

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45
Location
SPRING GROVE PA
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Have been running Mobil 1 0w20 in my 2018 Subaru Forester for 40,000 miles (since new) and have averaged (according to the car MPG display) 39.7 MPG for the last 5,000 miles. Decided to fill with Amazon Basics in 5w20 full synthetic during the hot Pennsylvania summer months. Have put 2,500 miles on the Amazon Basics 5w20 and my mileage has dropped to 37.7 - a drop of 2 MPG. Driving habits still the same and I'm the only driver. One difference is that I've been using my AC more because of higher temps this time of year. Is this a common phenomenon when changing grades as I have done? No other changes have been noticed, e.g., startup noise, etc. My intentions are to go back to the Mobil 1 0w20 next change which should be September when the temps average a bit lower. Your thoughts?
 
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771
Location
Muncie, Indiana
Originally Posted by IBelieveinlube
Decided to fill with Amazon Basics in 5w20 full synthetic during the hot Pennsylvania summer months. Have put 2,500 miles on the Amazon Basics 5w20 and my mileage has dropped to 37.7 - a drop of 2 MPG. Driving habits still the same and I'm the only driver. One difference is that I've been using my AC more because of higher temps this time of year.
5w20 and 0w20 should account for almost no difference in fuel economy infact with warmer weather the 5w20 may actually be thinner than a 0w20 at cooler temperatures at startup but at operating temp they are virtually identical, The A/C is the only thing that explains the difference. Oil doesn't usually change fuel economy that much maybe a couple percent when switching between grades (ie, switching a fleet from 5w30 to 5w20 may increase the fleet average fuel economy 2% or something) but 5% lower fuel economy between 0w20 and 5w20 would most logically be explained by using the A/C more often.
 
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14,573
Location
Upper Midwest
It's not because of the oil as that would defy the laws of physics. Both are 20-grade oils and no two oils of the same grade could possibly cause that difference. There are a myriad of environmental factors and personal habits that affect observed fuel economy. Anything the oil could do is way, way deep in the noise.
 
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1,569
Location
VA
Do you track mileage for each tank on your own? If so, how does the current mileage compare to last summer? My guess is that A/C use caused the mileage drop.
 
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1,324
Location
texas
you wont know for sure unless you dump the amazon mid oci and put in 0w20 and see if the mpg comes back. then dume the 0w 20 and pour back in the amazon and see if it drops. then reverse again. if you gass mileage follows the oil then you have a winner.
 
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14,573
Location
Upper Midwest
Originally Posted by danez_yoda
you wont know for sure unless you dump the amazon mid oci and put in 0w20 and see if the mpg comes back. then dume the 0w 20 and pour back in the amazon and see if it drops. then reverse again. if you gass mileage follows the oil then you have a winner.
That won't be conclusive at all. Once again it cannot be the oil and any environmental variables or personal driving habits will not be identical over the test period. As always, measuring something is the easy part. Ascribing it to one or more isolated variables is the much harder part.
 
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13,343
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1/2 hr N.E. of Detroit
AC running will definitely affect MPG, although I do believe Mobil-1 advertises itself as best oil for fuel economy. I would never expect Amazon Oil to keep up with Mobil-1 Oil, in any category of motor oil deliverance-services to our engines.
 
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1,971
Location
War Eagle
With Mobil 1 on rebate in fall and winter, why not simply use Mobil 1 in your choice of viscosity? I bet that 0w20 will be fine for year round use What does manufacturer state for oil specification?
 
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1,792
Location
South Carolina
Originally Posted by 77Se7en
I would never expect Amazon Oil to keep up with Mobil-1 Oil, in any category of motor oil deliverance-services to our engines.
I think you really believe that!
 
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1,223
Location
Indiana
Originally Posted by danez_yoda
you wont know for sure unless you dump the amazon mid oci and put in 0w20 and see if the mpg comes back. then dume the 0w 20 and pour back in the amazon and see if it drops. then reverse again. if you gass mileage follows the oil then you have a winner.
Well said. You could be a six sigma black belt!
 
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3,895
Location
SW Ohio
Originally Posted by IBelieveinlube
One difference is that I've been using my AC more because of higher temps this time of year.
Ummm, that alone could be the cause. Otherwise, you're comparing a 20-weight oil to another 20-weight oil.
 
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14,573
Location
Upper Midwest
Originally Posted by nascarnation
Originally Posted by danez_yoda
you wont know for sure unless you dump the amazon mid oci and put in 0w20 and see if the mpg comes back. then dume the 0w 20 and pour back in the amazon and see if it drops. then reverse again. if you gass mileage follows the oil then you have a winner.
Well said. You could be a six sigma black belt!
With all significant variables being uncontrolled?
 
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1,572
Location
WA
what is the cSt of both oils at nominal operating temperatures? In addition to ac, maybe Mobil 1 is more slippery. If the same, maybe Mobil 1 maintains its slipperiness better and/or longer during its usable life. Who's got more moly? I like moly. grin2
 
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3,940
Location
Decatur AL USA
Im getting 10% better mpg since June 03 compared to from May 01 to June 03. I could attribute that to the change from M1 5W-30 SN+ GF-5 to MC Blend 5W-30 SP GF-6 but instead I attribute it to a change in the color of my work shirts.
 
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21,836
Location
Dallas,Tx USA
Originally Posted by IBelieveinlube
One difference is that I've been using my AC more because of higher temps this time of year.
^^This is your guilty culprit.
 
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