How Much is too much?

[GoodferYuuu!]

Hi chatters,

another question that is hard to find the definitive answer to:

How much overfill is too much overfill?

I haven't looked, but she says the dipstick showed maybe 1/8 to 1/4 overfill after the infamous 5k oil change/tire rotation, etc. service. I have noticed a drop im MPG by about 1 or 2 MPG, but it was a bit colder in Beantown last week than it has been (we've only had it since August). I'm going to check the tire pressure and look at the dipstick myself Saturday, but I thought I should ask, so as to be prepared to act quickly and decisively!

Thanks,
Rob

[TonyPSchaefer]

There is a charged-carbon filter that is designed to absorb fumes and reduce emissions. Overfilling will damage that filter.
Overfilling can cause the gasoline to come spouting out the tank when you remove the nozzle.

In my opinion, too much overfill is any amount 0.001 gallons after the first click.

[brandon]

I think we're talking about oil overfill in this case, not fuel overfill.

[viking31]

<div class='quotetop'>QUOTE(TonyPSchaefer @ Oct 20 2006, 01:16 PM) [snapback]335626[/snapback]</div>

There is a charged-carbon filter that is designed to absorb fumes and reduce emissions. Overfilling will damage that filter.
Overfilling can cause the gasoline to come spouting out the tank when you remove the nozzle.

In my opinion, too much overfill is any amount 0.001 gallons after the first click.
[/b]

To stray from the original post a little how can one tell if the carbon filter is damaged as a result of a fuel overfill? I suppose mine probably is toast because a few times I had fuel nozzles not shut off when they should have (even got the infamous burp once). And if it is damaged, other than increased emissions, are there any other problems that might be caused by a damaged carbon filter?

I imagine thousands (if not tens of thousands) of Prius's are probably now sporting damaged carbon filters due to occasional overfilling. It would be difficult to believe this is a problem with most other automobiles. I would assume most automobiles are designed with the proper valves in the vapor lines to prevent backflow to the carbon filter canister. Too bad Toyota could not design the fuel system to prevent damage to the filter as a result of overfilling.

Rick
#4 2006

[GoodferYuuu&#33;]

To get back to the ooriginal post:

Yes, oil is what I was asking about. Can anybody help with that question? Also, the question that TonyPSchaefer answered (except about gas), which is "what happens that kills mileage?"


This is what's great and difficult about a forum; it's hard to glean the answer from everybody's answers, opinions and comments, but you get an unbeleivable amount of information.

[Beryl Octet]

<div class='quotetop'>QUOTE(Gadgety Bourgeois Type @ Oct 20 2006, 02:08 PM) [snapback]335659[/snapback]</div>

To get back to the ooriginal post:

Yes, oil is what I was asking about. Can anybody help with that question? Also, the question that TonyPSchaefer answered (except about gas), which is "what happens that kills mileage?"
This is what's great and difficult about a forum; it's hard to glean the answer from everybody's answers, opinions and comments, but you get an unbeleivable amount of information.
[/b]

I'd always heard the concern with oil overfilling is not a mileage (economy) impact, but increased engine wear or damage due to the crankshaft frothing the oil into a foam, which has poor lubricating qualities. I guess increased friction in the engine could result in lower mileage, but I'd more concerned about the engine.

I've never had good luck unscrewing a drain plug and letting just a little oil out. Your best bet might be to remove the oil filter and pour out the contents, depending on how much it's overfilled.

[galaxee]

basically, 1/4 inch is nothing. if you're really picky and want to spend some more time at the dealer you could bring it back.

lots of discussion of this here

but i'm gonna cheat and just copy one of my posts from that thread here:

excess oil will return through te PCV system into the intake, and what gets into through the air intake will be burned with the gas, which isn't so hot for mpg, and what doesn't get carried with the air into the cylinders gets pooled in the bottom of the air intake. modern air intake manifolds are designed to direct airflow in a certain manner. the oil in the intake changes the airflow pattern, changing how well the gas is dispersed.

as far as oil overfill relates to pressure inside the engine, it's known that increased pressure inside the crankcase wouldn't affect mpg. extra oil inside the engine cannot physically restrict engine operation. it would, however, affect the oil leak situation. (blown out seals from too much pressure and in extreme situations, oil blowing past valve seals)

[GoodferYuuu&#33;]

Beryl Octet,

Thanks for the info. I wonder how much oil 1/8 to 1/4 inch on the dipstick amounts to. They charged us for 4 quarts, but, spatially, it seems to me a half quart would raise the level more than that. I guess it depends on how wide the oil pan is at the top.

Thanksto you too, mr science avatar guy!

[Beryl Octet]

<div class='quotetop'>QUOTE(Gadgety Bourgeois Type @ Oct 20 2006, 02:26 PM) [snapback]335672[/snapback]</div>

Beryl Octet,

Thanks for the info. I wonder how much oil 1/8 to 1/4 inch on the dipstick amounts to. They charged us for 4 quarts, but, spatially, it seems to me a half quart would raise the level more than that. I guess it depends on how wide the oil pan is at the top.

Thanksto you too, mr science avatar guy!
[/b]

As galaxee says, 1/8 to 1/4 inch over is probably not a big deal. At some point though, overfill too much and the oil will be in contact with the crankshaft. Not good. I'd have thought half a quart over would be much higher on the dispstick, so they probably just "eyeballed" the last half quart.

[GoodferYuuu&#33;]

<div class='quotetop'>QUOTE(Beryl Octet @ Oct 20 2006, 02:44 PM) [snapback]335688[/snapback]</div>

As galaxee says, 1/8 to 1/4 inch over is probably not a big deal. At some point though, overfill too much and the oil will be in contact with the crankshaft. Not good. I'd have thought half a quart over would be much higher on the dispstick, so they probably just "eyeballed" the last half quart.
[/b]

...and by "eyeballed" you must mean "charged me for". At least it was synthetic oil and not ex$pensive at all