Oil Overfill- Ask Toyota

in the 05 repair manual, spec is listed as 3.9 qts. i think they dropped it to 3.7 in more recent years, but at any rate that's the source for the number they use at most places. use the number toyota provides, assume it's correct, screw it up and you might get fired. that's about how the thought process goes.

DH uses 3.5 in all his prius oil changes, but he doesn't do many oil changes in the first place.

prius techs are always the ones under your hood for issues involving the HV system, but to change the oil just about anyone can do it.

 

I have seen all the posts about not overfilling the oil, but exactly why would we want to run less oil than the manufacturer recomends? 3.5 instead of 3.9 or 3.7?

 

<div class='quotetop'>QUOTE(05_SilverPri @ Mar 26 2007, 06:36 AM) [snapback]412256[/snapback]</div>

First of all, the issue of overfilling applies to almost every car. Not just the Prius. As a rule, you need to keep the oil level between the MAX and MIN mark on the dipstick. It's really not that hard to do.

As long as you are between the two marks, it makes essentially no difference what level you are at in terms of wear and tear on the engine.

What happens when you overfill the engine with oil? well, its kind of like overfilling your washing machine with water - it splashes all over the place, getting into places it really shouldn't. In the case of cars, it ends up carrying over into the air intake system through the casing vent - generally making a mess of things. Overfilling can also contribute to leaks through various seals (e.g., crankshaft) that may be just above the oil line.

 

If you look in the other thread about the oil level you will see a Toyota document that specifies 3.9 qts for the Prius. If this accurate (and I don't doubt it) then why do people think 3.9 is too much? Because the oil is above the full mark on the dipstick? If there is a discrepancy Toyota should be able to address this issue simply enough.

I seriously doubt if any service dept takes the time to make sure only 3.9 qts goes into the engine. They just put in the 4 qts because 1/10th of 1 qt can't make that much difference. Now, if 3.9 isn't the correct number then that is a problem that needs to be corrected by Toyota.

I would think that if Toyota thought this was a serious problem there would be more information from them on it.

 

<div class='quotetop'>QUOTE(05_SilverPri @ Mar 26 2007, 02:29 PM) [snapback]412417[/snapback]</div>

I would have to say the 3.9 is to fill a dry engine with no oil. Not all oil drains out so that would make up the difference.

 

<div class='quotetop'>QUOTE(fairclge @ Mar 26 2007, 02:47 PM) [snapback]412438[/snapback]</div>

That doesn't explain how the oil level would be 1/4" over the fill line in a brand new car as mentioned in the first post.

 

<div class='quotetop'>QUOTE(fairclge @ Mar 26 2007, 02:47 PM) [snapback]412438[/snapback]</div>

I just changed the oil today on my Prius for the first time. One good thing about doing it yourself is that you can take the time to let the oil drain, and get 99%+ of it out.

I refilled with pretty close to 3.9 quarts, and it worked for me. The level is at the upper indicator on the dipstick.

One thing about checking oil: you can have some oil on the dipstick which seems to indicate a higher level of oil than is really there. My guess on the original post is that oil level was probably okay. You have to look for the lowest level of oil on the dipstick, which is the actual oil level.

And even if it was 1/4" high, I doubt that would hurt anything.

Harry

PS: changing the oil in a Prius is easy: you don't have to jack the car up, and the oil filter is easy to get to. No excuse for anyone not changing their own oil, and saving $$$'s.

 

<div class='quotetop'>QUOTE(fairclge @ Mar 26 2007, 10:47 AM) [snapback]412438[/snapback]</div>

The 3.9 quarts specified is assuming that it is a dry engine or at least drained to a very high degree. Think of it as the maximum you can put in. When you fill the engine with oil, it is up to you to add whatever is the required amount to get you in the Min / Max range of the dipstick.... That could be 3.4, or 3.7... but it probably won't be more than the 3.9 quarts indicated.

In terms of filling it up, dealers and lube shops generally do not use quart cans like you would at home. They pump it out of a tank with a volume gage that is suppose to be accurate to the 10th of a quart. So, yes, they can put 3.9 quarts into your car.

 

<div class='quotetop'>QUOTE(05_SilverPri @ Mar 26 2007, 02:29 PM) [snapback]412417[/snapback]</div>

You mean like issue a TSB (Technical Service Bulletin) like they did in 2004. TSB EG050-04 says the oil level and viscosity are "critical for the proper performance" of the Prius. It goes on to state that a MIL may come on if the level or viscosity is ignored.

It does repeat the 3.9 quart amount, but if you believe that you probably also think the fuel tank takes 11.9 gallons. Toyota seems to ignore the difference between dry fill and refill in their documentation. This is not just a Toyota problem. Around 2001 to 2002 Audi reissued the oil refill requirements for A4/A6/A8 cars three or four times before getting it right. Of course, the Germans are more anal about getting their documentation correct.

- Tom

 

So they put out a TSB that restated what the original numbers were, which in mind only says to not go over 3.9. My question is what is actually correct for changing the oil and does 3.9 lead to the MIL or not?

 

<div class='quotetop'>QUOTE(Tom_06 @ Mar 26 2007, 11:56 AM) [snapback]412483[/snapback]</div>

I posted this TSB in another similar thread here today

http://priuschat.com/index.php?act=Attach&...ost&id=7096

All I can tell ya is that Toyota gratuitously delivers most or all Prius with excess engine oil on board. No idea why. In most cases this does not seem to lead to grief. If some do get the warning lights, it would be hard to be certain that engine oil overage is the only cause.

But it's very easy to fix. If you can keep the oil level between the two dipstick dots, everything is going to be OK. 3.5 US quarts will probably be enough. If not, just add a bit more.

As with many other Prius DIYs, I do not get excited over stuff like this (any more). Just set it right and change oil&filter on appropriate intervals. When engine oil (or something that very much resembles it) accumulates in the intake manifold, clean it out. When soot accumulates on the throttle butterfly, clean it off. Most of the time, you are going to be driving a car that boringly requires little or no maintenance intervention.

So, use all that excess car-fixing time for Priuschatting.

 

Indeed, exactly 3 US quarts is plenty for a (re)fill during an oil change. Mine has always gets that much at each oil change and the level on the dipstick is always halfway between ADD and FULL.

Why Toyota does not address the overfilled-at-delivery matter is puzzling, since they do warn against overfilling.

 

<div class='quotetop'>QUOTE(tochatihu @ Mar 26 2007, 06:12 PM) [snapback]412558[/snapback]</div>

I have purchased two Prii here in Delaware. Barb's in Febuary 2005 and mine in January of 2006. At the same time I know 5 other people who purchased them, mostly this year (one guy picked his up at the same time I got mine on 1/2/06). None of these cars were overfilled - they were all checked because of all the overfill stories I had read on this board and in Yahoo! groups.

Most of these cars were from Newark Toyotaworld. You might think the dealer was the reason for no overfills. Not so, they claimed they don't do anything but check the level when I asked. Also, their service department used to routinely overfill although they have learned better over the past year. So for some reason the cars are delivered here filled just to the full mark.

I have learned from removing oil from Barb's car and my friend's car after overfilled service that 1/4" over on the dipstick is about a cup of excess oil and 1/2" over is a bit more than a pint. I removed the oil using a pump that goes down the dipstick tube.

On my car, I take in my own oil (synthetic) and only bring 3 quarts. The level comes up 1/2 way between the add and full marks on the dipstick with a filter change. The service advisor says several people are doing the same thing and they are used to doing it this way.

Now if I could just get them to leave the tire pressures alone or at least fill them to the door sticker values. They consistently (yes, all 7 cars) deliver the cars with 31 psi all around and do 31 to 32psi after rotating them.

- Tom

 

<div class='quotetop'>QUOTE(05_SilverPri @ Mar 26 2007, 05:49 PM) [snapback]412541[/snapback]</div>

At the time the TSB came out, people were being told at some dealerships that the 10W-30 oil they used in most other Toyotas was just fine and some were seeing a quart too much oil. Personally I don't think 1/4" over does any harm (although I would correct it on my own car), but 1/2" does affect mileage a bit. I would definitely recommend removing oil if 1/2" over. My friend who had a 1/2" oil overfill did not get a MIL in 100 to 150 miles of driving before he brought it over to have me pump the excess out.

- Tom

 

In the 07 owners manual page 323 it talks about oil consummation by a new engine during the break-in period as being higher than normal during the first 600 miles. Perhaps the oil level is on the high side from Toyota for a new Prius due to this factor.
Lets not over think this process it not hard; middle of dip stick with cold engine is good I think and check it every fuel change and replace every 5K.

 

I guess that is also the point I would make - it isn't that difficult to get the oil level at an acceptable level if you do it yourself. If you don't, just ask the shop where you have it done to make sure they don't over fill it. And if they go over by an 1/8th or a 1/4 of an inch, don't freak out about it.