Oil Overfilled by 1/8 in is that a problem

what's wrong with having oil up to the full mark?

 

I have a drill with a little pump "you can pick one up at the marine store.... maybe even auto store" and the drill acts to spin the pump. One hose goes down into the dipstick tube and the other into a cantainer....

 

I don't think its bad.. maybe just not as good.. according to this oil instruction sheet made by prius owners.

 

that whole "ideal level 1/4 inch below" is opinion. i'm just saying that if the oil is at the full mark, why go through all the hassle of taking oil out, so that you may or may not see a 1-2 mpg increase, which has nothing to do with the level of oil in the engine anyway? if it's overfilled (and at the "full" mark is NOT overfilled), the excess has already run through the pcv system and done its thing. taking oil out won't do anything.

 

It may actually be the best way to test.... because I've always noticed an mpg increase when I change my oil with all my other rigs.... It just has to do with cleaner oil and better viscosity......

Those benifits from fresh oil could mask the effects of 1/4 oil below the fill mark.

By keeping the same oil, it keeps everything exactly the same except the oil level change.

 

meh. too much work for me to screw around with. oil is usually still honey colored in the prius after 5k miles anyway. like new. the fact that the oil level, when not grossly overfull, doesn't affect internal friction is enough for me.

but hey, if you wanna do all that, more power to ya

 

I just gotta get in the mood to do it.. it would be easy.... I already have that little drill pump... I use it for my boat... its ways easier pulling out the oil with it in my boat verses trying to pull the plug and make a big mess.

 

Oh, the thread that won't die. I'm not helping any.

Galaxee, you are a saint for hanging around and commenting on this issue and I support you all the way. Ok, that flag has been planted in the ground, however there are some points of logic that need to be gotten out in the air, again, regarding the issue of oil "overfill".

1. Engines are cooled by oil and liquid coolant. Some manufacturers are moving away from oil being an additional cooling sink and are moving over to dry sumps, however most manufacturers are sticking with running wet sumps vs. dry sumps because oil does offer some cooling features and a wet sump with surplus oil means that less care on the part of the owner/operator is necessary in maintaining sufficient oil levels. If the Prius were a dry sump vehicle everyone who is advocating a short oil fill would be in big trouble.
2. Said before, but .1 to .3 quarts is about 1-3 shot glasses of fluid. Spread across the entire surface area of the sump, it is an insignificant amount of fluid.
3. Crank slap at a 4 qt fill is impossible. The lowest point on a crank is still many inches above a 4 qt fill of the sump with the engine at rest. Additionally, when the ICE is in operation a significant portion of the oil in the engine is not in the sump but in the galleries and the filter. So the sump is drawn down further and the distance between the top of the oil fill and the crank is much greater.
4. The concept of increased oil system pressure with increased oil volume escapes me. If this were a gravity oiling system I might be able to see the logic, (more fluid, more downward pressure) however I'm really having a hard time understanding this. The item creating the oil pressure is the oil pump. The pump runs at a rate that is dictated by crank revolutions. Oil pressure is dictated by the oil pump, not the amount of fluid available to the pump for usage. Like all fluids, oil wants to assume the lowest position and will flow that way on its own. Oil will rise to the top of the level in he sump at the oil pump inlet, but it cannot go beyond that heigth without the pump's assistance. So, knowing that the pump is in control of the pressure in the oil system and it just isn't reasonable that it is affected by oil level kind of negates the logic that oil level = increased oil pressure. Or at least I cannot make the connection.
5. So, where is everyone going to put .25 of a quart of oil? Well, if you change it on your own no big deal. You just use a partial quart for your last bottle and you hold that around for the next oil change. But if you are using a dealer for service and providing the oil you want used, that is just a hassle, and frankly, wasting my breath to convince a service writer to do what I want them to do and then trusting those instructions to be communicated to the lube guy is something I just don't want to deal with.

I share all of your feelings about taking good care of this car. Not because I don't trust the technology or don't want to screw it up. Frankly the technology is proven and the vehicle is well built and well conceived, but this is a major expense for me and I intend on keeping it around a very long time. However, in every engineered device there is "margin". Define that as you will, but unlike an aircraft which is built for professionals to fly and maintain, this is a car. The engineering goals and logic assume that an idiot is going to be behind the wheel. Any manufacturer that assumes professional drivers and maintenance is making supercars that are way beyond the means of the folks posting here. Why are Ferraris and other supercars maintenance hogs? It isn't because they aren't well designed, it is because they are designed to be driven and maintained by pros, not the average joe.

Toyota makes very reliable vehicles, and some of the vehicle idiots I have met in my life have driven them, maintained them poorly and they are still running well. That means that Toyota's engineering goals include the "idiot factor". The Prius includes the "idiot factor" also. I've seen it over and over when reviewing system controlled battery maintenance and protection. It is there in the air conditioning system, in how it does its own thing often to the benefit of the vehicle. Toyota designed the "idiot factor" into this vehicle beyond what they do in the rest of their fleet. If they hadn't, hybrid technology would still be unavailable commercially as it would have required too much input and maintenance by the average buyer.

If that were the case, what conversations would we be having right now?

 

whew, an ally. thanks jerome for taking another shot and another perspective at this whole thing.