0w30 vs 5w20 nonscientific test.

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Vehicle: 2013 F150 with 5.0 V8. Recommended oil is 5w20. First oil change after purchase (@12k) was with Amsoil XL 5w20. At 22k (OLM <5%) changed to Amsoil SS 0w30; after reading numerous threads on the 30wt vs 20wt debate, wanted to see for myself. At almost 25k, changed back to 5w20 using Amsoil SS. What I noticed was that under light acceleration, there was a slight reduction in responsiveness, that I can describe as what seemed like a delay in the valve train adjusting itself to additional gas pedal; it seemed the thicker oil had more resistance to the change required for the timing advance. On longer trips(same as taken with 5w20), noticed a slightly lowered mpg. Not enough to be statistically reliable/significant, but enough to notice in both the mpg readout in the truck and hand calculations as well. On short trips in town, noticed a large mpg difference, from about 15 with 5w20 down to 11.5 with the 0w30(both indicated by vehicle). Since the around town driving is consistent short trips that don't vary much, this is more reliable than the long distance and is not really affected by wind. On startup with 0w30, noticed it cranked slightly slower as well as taking longer to crank. Power at full throttle did not seem to be affected, although the engine was not as free revving, perhaps the result of the delayed valve timing change. Part of the mpg could arguably be from winter blend of gasoline, which here in northern MT starts in mid to late September; however based on other threads/data on winter gas mpg changes, the magnitude of the in town mpg change can't be solely from the gas blend. As stated in the title, test was nonscientific. The only data that is not subjective is the mpg. YMMV, but I wanted to share the experience with BITOG, since there has been so much discussion about this issue. I made sure to try to objectively observe the changes in engine behavior during the test, and am pleased to report that the negative aspects noticed during the short run with 0w30 have gone away once it was switched back over. MPG remains to be seen as I just changed yesterday, but will keep an eye on it for the next few months.
 

Y_K

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0W-00 would give the best mpgs, in fact, it would defy Carnot Cycle. Even a sample non-SS variety
 
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If you want to take it one step further, get some Toyota Genuine 0w20 which is about the lightest 0w20 you can get and should have the biggest difference in short trips.
 
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Next time, take it to a garage, and have them put in either 0w30 or 5w20, but don't tell you which. Then drive it for a couple of months and decide about which oil they put in. Then ask them at the garage what is actually in the crankcase.
 
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Originally Posted By: A_Harman
Next time, take it to a garage, and have them put in either 0w30 or 5w20, but don't tell you which. Then drive it for a couple of months and decide about which oil they put in. Then ask them at the garage what is actually in the crankcase.
^^^^
 
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What time of year did you run these tests? Temperatures and fuel chemistry can make a significant difference in fuel use, far more than any oil viscosity change.
 
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Myths. Difference is miserable. I would not believe if topic starter sees the difference on tiny engine as Honda Fit. Not worth even to talk about big V8. I don't believe, period.
 
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Only way I can see this possible is if camshaft variatior acts differently with different oil viscosity.
 
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Originally Posted By: Kuato
Vehicle: On short trips in town, noticed a large mpg difference, from about 15 with 5w20 down to 11.5 with the 0w30(both indicated by vehicle). Since the around town driving is consistent short trips that don't vary much, this is more reliable than the long distance and is not really affected by wind.
So your non scientific test resulted in 15mpg for the 5w-20 compared to the 11.5mpg for the 0w-30 oil this means the 5w-20 is 30% more efficient than the 0w-30. Hmmmmmmmmmmm something is not right here.
 
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Thinner oil is going to have less energy lost to shear. You know you went too thin when you loose hydrodynamic mode and the engine knocks smile Ford likely employs wider bearing journals to support the lower operating viscosity. I have not researched this engine design. Thicker oil can retard the VCT sooner (lower rpm) if this is a constant variable hydraulic system with a 2 position valve and this will reduce low rpm torque.
 
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Originally Posted By: Danno
What time of year did you run these tests? Temperatures and fuel chemistry can make a significant difference in fuel use, far more than any oil viscosity change.
this
 
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The 0w30 is probably thinner at all temps below operating temps than the 5w20 is, courtesy of it's 0w cold viscosity rating. If it's not actually thinner, it will be very close. So, that kind of throws out short trip city driving mileage differences as being oil related...
 

Kuato

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Thanks for all the replies, apologies for taking awhile to respond as I have been in training class this week.
Originally Posted By: 901Memphis
If you want to take it one step further, get some Toyota Genuine 0w20 which is about the lightest 0w20 you can get and should have the biggest difference in short trips.
Originally Posted By: A_Harman
Next time, take it to a garage, and have them put in either 0w30 or 5w20, but don't tell you which. Then drive it for a couple of months and decide about which oil they put in. Then ask them at the garage what is actually in the crankcase.
Love both of these ideas.
Originally Posted By: Danno
What time of year did you run these tests? Temperatures and fuel chemistry can make a significant difference in fuel use, far more than any oil viscosity change.
From mid-August until two weeks ago. Lowest temps experienced were in the low 40s, highest topped 100F. Change in behavior was the same regardless of temperature or date.
Originally Posted By: chrisri
Only way I can see this possible is if camshaft variatior acts differently with different oil viscosity.
My thought exactly, it seemed that way since there was a slight lag with the 0w30.
Originally Posted By: Dallas69
I dont think you can feel anything between the two It is all in your head
Sorry Dallas, never said I felt a difference (in fact said the power was the same); I only said there was a slight hesitation with the heavier oil....see chrisri's quote above.
Originally Posted By: geeman789
The 0w30 is probably thinner at all temps below operating temps than the 5w20 is, courtesy of it's 0w cold viscosity rating. If it's not actually thinner, it will be very close. So, that kind of throws out short trip city driving mileage differences as being oil related...
Agreed that it was very close; I ran these oils on the oil viscosity calculator here,. It showed the 0w30 would be thinner to approximately freezing, then would be thicker all the way to operating temperature. So since all the driving was well above freezing, that would mean it was always thicker than the 5w20. One note -- cranking speed has remained slow, so will be testing the battery later this week.
 
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