My 2019 Miata runs 0w20 in winter, 5w20 in summer 2 OCI per year. Completely amateur opinion here, every one has a opinion. Once on the highway it is running hydrodynamic in the bearings at RPM. That means the only friction on the bearings has to do with oil viscosity. The other issue is piston rings on the cylinder. Too thick oil will actually eat oil and reduce oil level. My oil level is zero loss per OCI. Same with my 2008 Miata too. Too thin and you will see iron show up on a DGA. Balance is the key. HTHS is another way to look at the thick or thin debate. Every engine is different. Being on the freeway means you do not have a lot of fuel dilution. The other positive of the lower viscosity is better heat transfer.
MPG vs HTHS
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On my 07 Corolla it gets interesting. I currently favor Valvoline PB 10w-30 which is 3.5 HTHS.
With 0/5w20 and 5w30 the engine is silky smooth and I get really good gas mileage right after an oil change ~36mpg. Around 1,500-2,000 miles the engine noise picks up and the power decreases. I assume this is due to viscosity loss and cam phasing issues at the low end. The mileage levels out around ~34mpg, and somewhere around 4.5-5k it drops to 33mpg and tapers down from there.
With the Valvoline I get ~34mpg for the 5,000 mile interval. QS 5w-40 gives similar results. Rotella or Valvoline PB 5/40 is 33mpg.
A 20/30 pcmo saves me 2-3 gallons of gas over 5,000 miles.
With 0/5w20 and 5w30 the engine is silky smooth and I get really good gas mileage right after an oil change ~36mpg. Around 1,500-2,000 miles the engine noise picks up and the power decreases. I assume this is due to viscosity loss and cam phasing issues at the low end. The mileage levels out around ~34mpg, and somewhere around 4.5-5k it drops to 33mpg and tapers down from there.
With the Valvoline I get ~34mpg for the 5,000 mile interval. QS 5w-40 gives similar results. Rotella or Valvoline PB 5/40 is 33mpg.
A 20/30 pcmo saves me 2-3 gallons of gas over 5,000 miles.
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……too.
I have similar Toyota 1 zz fe and when tuning with low Hths 5w30 and 5w40 or 0w40 mobil fs at the freeway constant 140-150 km/h 200 miles distance, I cannot see any difference in mpg…
I have similar Toyota 1 zz fe and when tuning with low Hths 5w30 and 5w40 or 0w40 mobil fs at the freeway constant 140-150 km/h 200 miles distance, I cannot see any difference in mpg…
I think the.MPG penalty is much less than 1%.
I permantly switched from 20 weight oils to 5W-30 oil and see no measurable difference in my MPG.
I have precisely tracked the MPG to 1/100's precision in Excel spreadsheets
for my 4 J35A7 Honda Odyssey's for the years they were on 5W-20 and the years after the permanent switch to 5W-30. No difference at all.
0w20, 10w20, 0w40 have all been through my Mazda. No detectable difference in fuel mileage.
I did a similar test back when I had an 01 v6 escape. 5w30 5w20, 5w40. No difference.
I did a similar test back when I had an 01 v6 escape. 5w30 5w20, 5w40. No difference.
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What causes thicker oil to be consumed faster?
Instead of scraping the oil off which the oil control rings should do they hydroplane. There is a too thick point. Low tension piston rings?
Heavier weight oil to solve oil consumption problems
Heavier weight oil to reduce oil consumption problems
ricksfreeautorepairadvice.com
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Both are 20 weights, not sure if you gain much by switching. I guess if it was me I would use 5w20 if under 5000 mile changes and 0w20 if you were running over 5000 miles per change. But thats just me, I'm sure 5w20 is a bit cheaper.
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They don't specify how thick is too thick. Because they can't, because you can't really make a generalization like that. Yet the whole article reads like generalizations.Instead of scraping the oil off which the oil control rings should do they hydroplane. There is a too thick point. Low tension piston rings?
Heavier weight oil to solve oil consumption problems
Heavier weight oil to reduce oil consumption problemsricksfreeautorepairadvice.com
Tracking is one thing. Attributing a change or no change to a single variable is quite another.
Thank Kschachn. Very true.
I see in your signature you have some 300k+ mile vehicles.
Would you be willing to share your oil change interval in miles / months and also oil consumption if any,
and whether you have sludge / varnish under valve cover if any. And what brand, type, and viscosity oils you use.
I think the rest of us can learn from your maintenance practices
as whatever you are doing is working.
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Your right foot, a headwind, a heavier load, a hill or mountain will influence your MPG more than a viscosity change ever will.
I have gone up and down in viscosity...zero notable MPG difference.
I have gone up and down in viscosity...zero notable MPG difference.
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Indeed. The nicest Excel sheet wouldn't compensate for the flaws of missing a controlled environment for an appropriate measurement. These differences are way too tiny compared to inevitable slight variations in daily driving. I agree with roughly 1 % anyway.
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Indeed. The nicest Excel sheet wouldn't compensate for the flaws of missing a controlled environment for an appropriate measurement. These differences are way too tiny compared to inevitable slight variations in daily driving. I agree with roughly 1 % anyway.
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I read an interview many years ago done with the Toyota Engineers - when I bought the Toyota in my sig that specs 0w-16. I recall them sighting a 2-3% increase in mileage across the fleet. Of course individual situations dictate and as mentioned, there is no way to tell in one specific case, however even if you use the 3% (which I think is quite high) it equates to 1 gallon less per 1000 miles in my Toyota. So rounding error in my world. You would save more slowing down a couple mph.
Now if your an engineer trying to meet CAFE rules - 3% is absolutely huge.
Now if your an engineer trying to meet CAFE rules - 3% is absolutely huge.
Just less VII to shear. Not a big deal. I drive short trips and rarely get oil temps up.
Under a testing environment of 0w20 vs 5w30 the gain in fuel efficiency is around 2% by using the 20w.
www.sae.org
Remember automakers take a holistic approach to improving FE when designing a vehicle. Examples : Stop/start, EPS, 20w oils, brake Regen, tire compound/construction, etc. It all adds up.
Here's a comparison of similar BMW models. Same engine but the newer model has
EPS, Stop/Start, 8sp AT, and runs on a 30w with HTHS under 3 5cP. Fuel burned (gallons) in combined cycle is 4.0 vs 4.5 per 100 miles
Study on the Influence of Low-Viscosity Engine Oil on Engine Friction and Vehicle Worldwide Harmonized Light Vehicles Test Cycle Fuel Economy
To study the mechanism of the effect of low-viscosity oils on engine friction loss reduction so as to improve the vehicle fuel economy of the Worldwide harmonized Light vehicles Test Cycle (WLTC) by upgrading the Society of Automotive Engin
Remember automakers take a holistic approach to improving FE when designing a vehicle. Examples : Stop/start, EPS, 20w oils, brake Regen, tire compound/construction, etc. It all adds up.
Here's a comparison of similar BMW models. Same engine but the newer model has
EPS, Stop/Start, 8sp AT, and runs on a 30w with HTHS under 3 5cP. Fuel burned (gallons) in combined cycle is 4.0 vs 4.5 per 100 miles
Compare Side-by-Side
Compare the MPG of cars and trucks side-by-side. Compare the gas mileage and greenhouse gas emissions of new and used cars and trucks
www.fueleconomy.gov
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If you were commuting 3 miles each way in a place with real winter, I'm sure there would be some easily measurable difference between 0W20 and 5W30. But for more normal driving habits its pretty hard to measure at home.
You’d probably need a sample size of 1M cars with the exact same engine and driving patterns to determine any difference whatsoever between a 0w20 and 5w20. The ONLY time a 0w20 would show any improvement in any testing would be in cold weather pumpability, and then only below -30F.
Considering that you’re in So Cal, you could more likely than not run 10w30 vs 0w20 and not see any difference. As kachachn has noted, in a sample size of one there is way too much testing noise to be able to statistically prove the difference is solely attributable to the oil.
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