Oil Level and Fuel Economy

[MadMax]

OK, I have been interested in the level of oil most people keep their Yaris at since I have been trying to find ways to counter the "winter gas syndrome" that has dropped my MPG average (from 36-38 MPG during the summer to 32-34 during the winter. Note I am running 215/45ZR17s Riken Raptors on my 08 auto hatch).

I came across this web site: Exstrom Laboratories - How To Increase Your Gas Mileage and note FAQ #22 states:

Can a low engine oil level reduce my gas mileage?
Yes it will. A low oil level increases engine friction, and so reduces gas mileage.

But my question is does keeping your oil level at half or below on the dip stick help increase gas mileage? Mine is usually close to the upper point on the stick, and if anyone has any firsthand experience with keeping it lower I would like to hear their results.

Cheers! M2

[127.0.0.1]

Originally Posted by MadMax

OK, I have been interested in the level of oil most people keep their Yaris at since I have been trying to find ways to counter the "winter gas syndrome" that has dropped my MPG average (from 36-38 MPG during the summer to 32-34 during the winter. Note I am running 215/45ZR17s Riken Raptors on my 08 auto hatch).

I came across this web site: Exstrom Laboratories - How To Increase Your Gas Mileage and note FAQ #22 states:



But my question is does keeping your oil level at half or below on the dip stick help increase gas mileage? Mine is usually close to the upper point on the stick, and if anyone has any firsthand experience with keeping it lower I would like to hear their results.

Cheers! M2

if you can keep the oil right at the minimum line, the pump will not scavenge air....

do not go below the min line

all you will get is weight savings from the lack of an extra quart of oil. it is
practically useless. but anyway yes gas savings with minimal oil, and there will be no added friction unless the oil pump can't get oil. hence, do not go below the min line

[djct_watt]

Originally Posted by MadMax

OK, I have been interested in the level of oil most people keep their Yaris at since I have been trying to find ways to counter the "winter gas syndrome" that has dropped my MPG average (from 36-38 MPG during the summer to 32-34 during the winter. Note I am running 215/45ZR17s Riken Raptors on my 08 auto hatch).

I came across this web site: Exstrom Laboratories - How To Increase Your Gas Mileage and note FAQ #22 states:



But my question is does keeping your oil level at half or below on the dip stick help increase gas mileage? Mine is usually close to the upper point on the stick, and if anyone has any firsthand experience with keeping it lower I would like to hear their results.

Cheers! M2

You need to re-read the statement you quoted. If you take their advice as fact, then there is no arguing about it. If you want to decrease your gas mileage, then you want to keep your oil low. The quotation says that "low engine oil REDUCE[S] gas mileage." Now if you wanted the opposite, and you wanted to increase your gas mileage, then you would want to make sure that your oil level is NOT low. I'd go back and re-read the article carefully.

Secondly, if you were talking about weight savings (which I don't think you were), it would be pointless. You'd be better off going on a diet or cutting your hair. Half a quart to a quart of oil's worth of weight is not worth ruining your engine. Just make sure you aren't over filling. In fact, you'd probably consider taking ex-lax before every drive if you were really concerned with motor oil weight.

[Loren]

Geez. Keep the oil full, people.

Run 0w20 if you want to, but keep it filled to spec.

[MadMax]

Not talking about weight savings (which would be nominal at best), nor keeping the oil level below the minimum amount (any fool knows that's not a good idea).

What I was wondering was if the Yaris ran more efficiently with the oil level at the halfway point or slightly below versus at the upper levels. I know in the oil change thread it states it is better not to fill it up past the mid-way point, just wondering if there was a fuel-efficiency reason for that...

[Loren]

The only possible benefit would be the possibility of the crankshaft counterweights slapping through the oil in the bottom of the oil pan less. But, on an uber-efficient modern engine such as this, I have to imagine that the engineers would have thought of that and it's probably something they've already accounted for.

Don't OVERfill your engine oil, but by all means FILL IT UP when you change the oil.

[Yaris Hilton]

Originally Posted by MadMax

I know in the oil change thread it states it is better not to fill it up past the mid-way point, just wondering if there was a fuel-efficiency reason for that...

There is no good reason for that. The advice to which you refer is erroneous.

[docB]

Does my Yaris 1.5 have a windage tray? Windage, oil hitting the crank, is a real power, therefore economy killer. I refilled to the mid-point on the stick with 5-20 synth. I'll keep an eye on it.
doc

[UTVitz]

you have a timing chain that is constantly dipping in the oil so I would suspect the same is true for the crank as it comes around. 5-20 is lighter than 5-30, it might render some savings. I keep my oil full and still see 42-45mpg traveling a mix of city/hwy. I really don't think messing with oil weights and levels will render the same results with increasing fuel economy as does the way people drive their car-slow down and no jack rabbit starts-but people don't want to hear that.

[jambo101]

I like to keep the oil as full as possible as i believe the oil dissipates some heat from the engine.

[SpaceShot]

Keep it between 3.0 and 3.3 qt for the 1.5 engine.
Overfilling to 4qt or underfilling at 2.5qt will both cause a slight decrease in MPG not to mention the excess wear.

You might put in just 3 qt if you were keeping the filter on for some reason. But it is such a small filter and relatively easy change out that I don't see any reason not to change the filter each time.

[sbergman27]

Originally Posted by jambo101

I like to keep the oil as full as possible as i believe the oil dissipates some heat from the engine.

More than that, it works the oil significantly less. People don't talk about it much... but consider the 1976 Cadillac's 8.2 Litre engine, with 5 quart lubrication system. Compare that with, say, the Geo Metro's 1.0 litre engine with 4.3 quart lubrication system. And then consider the one-size-fits-all 3000 mile oil change for all cars mantra which so many people espouse. What if your oil pan were as big as your gas tank? How many miles could you reasonably go between oil changes?

Topping off the oil has also been shown to inject new life into worn oil. Paradise Garage did an interesting test with Mobil 1 which demonstrated that effect.

-Steve

[why?]

3000 miles is a great number to guarantee the oil has barely been broken in, therefor allowing oil companies to make any guarantee and allowing them to make tons of cash. I'd bet the same for the oil storage size.

OIL THREAD! OIL THREAD!!!

lol. under filling the oil is just silly.there are literally dozens of better ways to see better fe.

[sbergman27]

Originally Posted by why?

3000 miles is a great number to guarantee the oil has barely been broken in,

Indeed, I have seen indications from more than one source that wear is actually *greater* during the first 3,000 miles than during immediately subsequent miles. I'm not certain why that would be. But I currently allot the claim some credibility.

-Steve

[Yaris Hilton]

There's no plausible physical mechanism for that. I'd give it zero credibility.

[sbergman27]

Originally Posted by Yaris Hilton

There's no plausible physical mechanism for that. I'd give it zero credibility.

Skepticism is reasonable and appropriate. I have, however, seen this observation reported in a few places, backed by actual experimental data. For example:

http://tinyurl.com/35fn8

-Steve

[Yaris Hilton]

Actual experimental data often misses some unrecognized variable. I remain skeptical that there's some "breakin" process that benefits the antiwear properties of oil.

Closest I can imagine for a plausible mechanism would be suspended sooty particulate matter holding the bearing surfaces apart when the engine's shut off and the liquid oil wedge goes away, and on startup rolling like little ball bearings till the oil wedge rebuilds and separates the sliding surfaces. That's the alleged principle of solid lubricants like graphite, "moly," and Teflon in oils. The sooty glop is generally held to be abrasive. Perhaps it's not always so?

[sbergman27]

Originally Posted by Yaris Hilton

Actual experimental data often misses some unrecognized variable. I remain skeptical that there's some "breakin" process that benefits the antiwear properties of oil.

A very reasonable position to take. Just between you and me, I'm a bit skeptical of the general reliability of UOAs, and people's interpretations of them. Tribology is not a simple subject.

Closest I can imagine for a plausible mechanism would be suspended sooty particulate matter holding the bearing surfaces apart when the engine's shut off and the liquid oil wedge goes away, and on startup rolling like little ball bearings till the oil wedge rebuilds and separates the sliding surfaces.

That's kind of what I was thinking, as well. I'd say that "further research is needed in this area", as they're fond of saying at the end of scientific papers.

That's the alleged principle of solid lubricants like graphite, "moly," and Teflon in oils.

Hey! Remember Arcographite? I used to use that in my 1968 Cadillac back in the late 70s or early 80s. Messy, messy stuff!

-Steve