Noticed a big MPG improvement going to Syntec 0w20

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The car is a 2000 Honda Insight. The transmission is failing, the battery is failing, I bought it cheaply, but it keeps carrying on. I had it running a pretty long oil fill of 5w30 conventional oil. Factory spec is 0w20. The car always got between 50-60mpg on a tank. After changing the oil with Syntec 0w20, my mileage has mysteriously improved. I don't know if this is due to other factors such as changing to winter blend fuel, or the milder weather letting me go without A/C, but I haven't seen 70mpg on the FCD before, and my mileage right now is around 71.9mpg in mixed driving. Big difference! There isn't much point to this thread other than to say that in a Honda Insight, you need to run the factory specified weight of oil to get the best fuel economy. smile
 

Nick1994

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Did you perhaps tell a neighbor or a friend you were going to a thinner oil to see what it does to mpg and they sneak over at night with a gas can and add some gas to your tank? Lol
 

L_Sludger

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Haha, no. The car's fuel consumption monitor gives MPG insight in real time. I don't have any guesswork to do with fillups except to validate the accuracy of the computer.
 

L_Sludger

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Originally Posted By: splinter
Wow how did those antiquated Honda engineers miss such a simple and effective modification? wink And I envy your miserly consumption!
The best thing about this little car is that its 2.5L oil capacity lets me use the 5L jug of oil for two oil changes.
 
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Originally Posted By: splinter
Wow how did those antiquated Honda engineers miss such a simple and effective modification? wink
Modification? Factor spec is 0w-20. The OP just chose not to run it previously.
 
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I suppose the half-dozen or so hamsters that power the exercise wheels in the Insight appreciate the lower drag of the 0w20!
 
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Originally Posted By: A_Harman
I suppose the half-dozen or so hamsters that power the exercise wheels in the Insight appreciate the lower drag of the 0w20!
....this is an Insight, not a Soul.
 

gathermewool

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When did you change the oil? It's impossible that the oil change resulted in a 20%+ increase in gas mileage. There's just not that much to be gained.
 
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Its fall, we are in the middle of switching out the epa summer gas, and reduced Air Conditioner use. All that combined with changing the oil from the worlds thickest 5w30 to thinnest 0w20.. its possible. L_fudger has another FUD post but at least its not a total unbelievable/backfire this time :P
 

L_Sludger

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This car has lean burn functionality. My other Insight had it too. The car had issues going into lean burn with the heavier oil, thereby accounting for a drop in MPG. Whatever it was, the correct viscosity oil as called for by factory specifications brought my car's MPG up to normal. The MPG was subpar beforehand and I couldn't figure out why.
 
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As long as you're happy then we're happy too.
Originally Posted By: L_Sludger
This car has lean burn functionality. My other Insight had it too. The car had issues going into lean burn with the heavier oil, thereby accounting for a drop in MPG. Whatever it was, the correct viscosity oil as called for by factory specifications brought my car's MPG up to normal. The MPG was subpar beforehand and I couldn't figure out why.
 
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No wonder item number one focus on the NHTSA CAFE hit-list is viscosity... They claim that it's the least cost option to the consumer for improved mileage, and I guess that this proves it in spades.
 
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This is proof? So you lock, stock and barrel believe that it wouldn't go into lean-burn due to the viscosity? Once again you adapt the circumstances to support your crusade.
Originally Posted By: Shannow
No wonder item number one focus on the NHTSA CAFE hit-list is viscosity... They claim that it's the least cost option to the consumer for improved mileage, and I guess that this proves it in spades.
 
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Originally Posted By: kschachn
This is proof? So you lock, stock and barrel believe that it wouldn't go into lean-burn due to the viscosity? Once again you adapt the circumstances to support your crusade.
Do you even READ what you are responding to ? where, exactly did I say that ?
 

L_Sludger

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He's talking to me, I think. The car is finicky about going into lean burn. In lean burn the car makes only a few horsepower and consumes extremely little gasoline, at an AFR of 22-24:1. Everything needs to be working optimally to stay in this mode at highway speeds. Incorrect viscosity, in this case, may have narrowed the effective lean burn window for my driving profile so that my fuel economy was reduced. It may, I postulate, have thereby been expanded to its proper operating envelope once I changed the oil to the correct, factory-mandated viscosity. The effect may also have been in my head. Although recently I have been hauling hundreds of pounds of supplies from the stores to my home (see the ebola thread, I'm stocking up) - the MPG for the last 230 miles is now averaging at 68.9. It is still above the norm, though.
 

L_Sludger

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Originally Posted By: Shannow
L_Sludger So tip in/tip out of lean burn is either vacuum, tps, or some other load dependent thing ?
I observe that it generally requires the throttle to be at a certain position to engage lean burn, depending on the gear. When lean burn is engaged, it's like an 'anti-VTEC' and with careful throttle manipulation I can keep the car in that mode within a range of throttle positions. However, while it is in that mode and getting high MPG, it will generally lose speed going up an incline, so I'd have to kick out of that mode by increasing the throttle beyond the threshold, which then engages the electric assist to help in tandem with the motor at stoichiometric. Some Insight owners have modified their cars to provide electrical assist manually, even during lean burn operation. This, with a good enough battery pack, allows them to cruise most of their way to their destination in a super-efficient mode. They tell tales of getting 100mpg and more. Once more I have to remind our dear audience that it's unreasonable for them to expect a significant MPG gain in their normal, non-hybrid motor vehicle when changing from 5w30 to 0w20. Even a 1MPG gain would be tough to quantify in a statistically significant manner. I am just sharing that changing from an incorrect viscosity, to the correct viscosity, in my application, which is known to be very sensitive to every little operating variable, has within a limited sample set so far indicated a large - 5-7mpg's worth - overall improvement in MPG.
 

L_Sludger

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My fuel economy continues to plummet. Now I'm down to 68mpg for the tank. Must have been placebo effect.
 
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