Hi, i have the exact problem.

I just bought my jazz GE8 2012 for 5 months old now, and it is -+ 4200 km already
. I have not serviced my car since the book says i need to get a general check up for the first 1000 km ( no oil, filter changed..it was just a general check up ). And the first service should be 5000 km.

Usually i get average fuel consumption around 12.5 - 13 km / liter with combined route ( traffic jam everyday ) Full tank is around 33 liters, and i always re-fuel once a week full tanked.
So, 33 liters i get -+ 350 km..i even reached 400 km once due to went on a trip ( less traffic on highways ).

The thing is, i've pour some fuel injection cleaner like a month ago. put them together with full tanked fuel. The first 2 days was like i did not notice anything at all, but then when the tank is empty i notice that i've only reached 300 km. and my average is like 8 - 9 km/liter.

My route is combined with highway, most of the time is traffic jam. I'm not an aggressive driver, in fact i'm very concern about the fuel so i respect the pedal.
No driving behaviour changed at all, same route, same humidity, the car is new.

Now i have never reached 11 - 13 km / liter anymore, it barely reaches 10 km/ liter.
And when the car idles the average fuel information display changes..WTF? even when the car stops..

I mean was that fuel cleaner the culprit? or ECU's error ? but i really noticed that my car's fuel consumption is more than before.

This is not the first time i have a GE8, i have this car twice and i know this car has a good fuel efficiency

UPDATE : I've just checked my tire preassure and it's normal.

 

Overfilling by that much will have an effect on mpg and power output also. 1/2" over full mark on dipstick is probably one quart too much oil. When I change my oil and filter it never goes up to the full mark (only halfway between lower and upper IIRC). So 25% too much oil and slightly heavier weight also. All that extra oil causes the engine to work much harder.

Not exactly apples to apples but I bought a scooter once that had the oil overfilled. Approx 25% overfill also, after changing the oil and refilling to the correct level I picked up a true 5 mph in top speed, from 49 mph to 54 mph without any other changes. Granted a 125cc air cooled engine versus the Fit might not produce the same 10% increase in efficiency but his power and mpg will go up after resetting oil level so he should do that asap as you suggested. I would do a complete drain and refill per specs. Simply draining down to dipstick upper mark will still be overfilled.

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A 125cc air cooled 4 cycle scooter engine is probably using splash lubrication instead of a pressurized oil system. In these engines, the crank needs to contact the oil. Too much oil, and yes, the engine is wasting energy beating the oil.

If there is too much oil in the Fit to the extent the high level causes the crank to beat the oil, you'll have worse problems than higher fuel consumption (I alluded to above). I don't think half an inch above the high mark is there, but it would concern me.

Filling halfway between the full and add marks on the dipstick will reduce the oil volume in your Fit about 13% (0.5 quarts out of 3.8; less than I thought). Adding oil to the upper mark on the dipstick is not "overfilled."

When changing your oil, do you get out the measuring cup?

 

Oh definitely yes, I don't fill based on the dipstick. I refill at oil changes using an exact measurement of 3.8 as I always replace the filter. But I've noticed afterwards that it doesn't go to the upper dipstick mark. I do not add more than 3.8 (actually 3.6 liters so a hair over 3.8 quarts) to max out the dipstick as I trust the Honda spec'd volume more than the dipstick accuracy. Not sure if my dipstick is typcial or not.

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Silverbullet (as well as the closet oil obsessive compulsives)

To further derail the thread, I don't understand the logic on why you shoot for max on the dipstick, especially if your opinion is that that overfilling quickly leads to performance loss.

If you driving on anything other then perfectly flat road at perfectly constant speed, then some of the oil will slosh up and down and produce the same situation as you envision happening with the 1" overfill.

So this train of thought says then you should be shooting for the min or middle of the dipstick and shortfilling to minimize that behavior

I'm not saying I agree with these assumptions in the first place as I'm in the "just dump 4qts in" crowd, but just trying to point out the flaw in the logic.

 

The only time I "overfill" is for cars that see very high rpm with poor head drains and/or have large journal bearing turbo center-sections to feed..

 

I fill to top of dipstick. Put in 3.5 Q, start car, turn car off, let sit for a minute or two, check dipstick, usually at half between dipstick marks, add a little bit more ~1/4 Q = ~3.8ish

I don't think wrong viscosity would change fuel consumption nearly that much, at most they'd use a 5W30 or something similar.

 

You misread. I don't care about the dipstick just stating the observation for my car. I put in exact amount of oil and call it a day. Check dipstick only for reference and have never had to add oil between changes either as level always stays above lower mark. Use MM only for intervals so 8-11K miles between changes.

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High oil levels will result in lower HP and gas mileage BECAUSE the excess oil gets "wrapped" around the spinning crankshaft creating more drag on the spinning crank.

There is a great video on youtube if you search for it explaining this phenomenon. They have a clear oil pan and the oil just wraps around the spinning crank like salt water taffy.

While the Fit has a stock "windage tray" to help prevent this problem it gets defeated by overfilling with oil.

 

Sure in theory if you do something like doublefill the oil, that's not good; but back to reality, people are suggesting to the OP that 1/2inch over or even 1quart over is causing 25% loss of MPG.
If you think the tolerances are so precise in a honda Fit that an extra 1/2 inch of oil is causing the crankshaft to touch oil, you are off in theorycrafting land where engines are continuously running and never shutdown or startup, and cars never change speed, turn, or go up and down hills.

 

This is correct.

 

To add to the correction, oil pressure pumps are positive dispolacement pumps which means they have no real limit on the pressure they can provide except the power source. The height of the oil one greater than the intake of the pump have zero affect on the ability to provide pressure.
You may want to check the effect of viscosity by filling a lab fill pipet with 10W-30 weight oil and see how long it takes to drain compared with an equal amount of 0W-20 oil under same condditions. We will do it here as sopon as we find some 10W-30 oil, not plentiful here. That will show the effect of the change in viscosity. those pipets have small valve openings so the flow is not great.


OK one of the techs rolled in with an old can of 30 weight oil. Its not 10W-30 but it still took more than 3 minutes to drain from 20ml to 19 ml; on the oither hand used 0W-20 oil from a recent oil change drained 20ml to zero in 25 seconds.
I am the first to say it wasn't as good as lab conditions but even then we were stunned by the results. Both times the pipet was first leaned with WD40 and injector cleaner, which drained about the same as the 0W-20.
I conclude that indeed the pumping loses for the oil pumpo can result in lower mpg's. I won't say its 25% but it could be considerable.
Note that the pump power is a significant part of the losses at 30 to 60 mph but the friction losses aren't much different. Considering that the oil pump consumes a couple horsepower in that street range thats likely to be 50% of the loss in efficiency. It talkes only 5 to 10 hp to propel a Fit in that speed range so doupling the oil pump power required jumps from 2.5 to 5 hp. Guess what. A change of 2.5 hp easily can result in a 20% loss in power efficiency - and mpg.
Now don 't get your underpants in a tightwad; I'm the last to say for certain that was the reason for the mpg. There are so many other variables associated with driving, gas refills, and road conditiuons that I'm justt offering possible causes and having a little fun.
If I were the OP I'd change my oil and filter with 0W-20 oil and Honda fikter and see if the mpg went back to the prior mpg. If it did, that Ford dealer and I might have a conversation about a refund.
Have at it.

 

Like maybe 2%?

 

I cheated. Talked to my old cohorts at oil company and they won't go for my 25% but they won't go as low as 2% either. There's a lot more work to pump 30 weight versus 0 weight fluids of ant kind.

 

Horseshit, Mahout, we're talking 0W20 vs 5W20 or even 10W30, not 0 weight vs 30 weight.

 

You should listen to steve, he's got a PhD in Horseshit.

 

Granted, it was used 0W-20 versus new 30 weight but that a lot closer than 0W-20 vs 05W-20 and probaly not that much different than 0W-20 vs 10W-30.
There's a real big reason why you can't use 10W-30 oil in trucks in the arctic; You must use 0W-20 oil if you want the engine to even turn over.
Hey, try the experiment too using a simple container with a very small hole at the bottom.

 

It is correct that overfilling the frankcase adds losses to the efficiency of the engine. Causing the crankshaft to have to plow through a deeper pool of oil is power hungry especially if the oil is thgicker. There is also the loss in pumping air back and forth between cylinders because of the reduction in 'air' area between cylinders. hence the reason for dry sump lubrication. And of course, the loss from pumping heavier oil affects all of them plus pumping losses. All of these can result in substantial mpg loss.

 

Not sure what your rant is about.

This is like responding to someone saying drinking a 17oz soda:
"Consuming too much soda will result in diabetes and death, 16oz is the limit you should drink".

There is a scale and tolerances to everything.
It isn't black and white where you are 1drop overfull and suddenly your car is shit.

 

My rant is simply a list of things that will reduce the efficiency of an internal combustion engine relating to oil:
1. thicker the oil the greater the loss due to oil pump effort and rotating the crankshaft thru the oil
2. the higher the oil level the less room between the crankcase cylinders for air to pump from one cylinder to the other as the pistons go up and down so the efficiency loss is greater
3. the deeper the oil in the crankcase the harder it is to rotate the crankshaft so losses increase
When you design an engine its one the first things you work on. And why dry sumps are preferred and why pulling a vacuum on engine crankcases are common in GP engines. you'd be surprised how much work is involved in those pistons pumping air back and forth.
friction loss containment comes next. And why those who compete in mpg contests always fill thed oil to a quarter or two-thirds the way between low and full on the dipstick. Racers will do that too. If you can't dry sump, come as close as safe to it.(autocrossers are very careful due to the violent changes in direction trhat sloshes oil about maybe uncovering the oil pump intake).
And actually there are some things you don't have a tolerance, just a limit.