I'm worried about the following.
I was on a short drive home from my Porsche dealer (had to replace the RMS) and decided to check the oil level before I bring the car home. The car was warm and I'm sure I checked the oil level correctly. It showed one third above the minimum level so I decided to add a tad more oil to bring the oil level to two thirds above minimum. I've added 0.4liter (according to the owners manual one third is equal 0.5liter) but when I checked the oil level again on my drive today it showed that it's above the maximum.

Car is a 997.1 GT3

What's wrong? What if it's really overfilled? Should I try to drain some oil? If so, how should I do that?

 

I have found the most reliable oil level readings are obtained when (1) the car is completely warmed up (after a drive), and (2) the car is on absolutely level ground. Even small deviations from level can affect the reading. Make sure that these conditions are met so that you can trust your readings.

 

But assuming that after repeated checks at a consistent temperature and location the level is still showing high, I would do the simple loosening of the drain plug, remove it and quickly plug the hole with a finger before more than 1/4 pint has drained, have someone swap the crush washer and screw it back in. Sounds scary but it works just fine. Just make sure the area is completely free of dirt (around the plug), wear surgical gloves to protect your hands and to seal better at the plug hole.
With the plug bolt hanging on by just 1/2 a thread, it barely drips so you have a lot of margin for error in getting the plug in and out.
Oh, and yes, I have done this before...

 

Both the above mentioned conditions were met. I measured the first time and the second time at the exact same spot when the car was warmed up and after a drive of approx. 15miles. The first time it was one third above minimum and the second time (after i filled up 0.4liters) it was above maximum.

 

An extra .5qt/.4l won't hurt anything, next puff of smoke at startup will have you back at topped up level.

For future reference don't bother adding until the gauge is at the bottom and flashing, or when you see a 'low oil level' warning in the inst cluster - that comes on when you're approx 1qt/1l low, at which point there's still over two gallons onboard.

 

I did that once, brought it to the Service Center; they told me to just let it burn off...

 

adding 0.4L won't do a thing to it even if you add it on top of Max level.

 

Why would too much oil be burned off? Does it get to the intake section somehow?

 

Oil seeps into the horizontally opposed cylinders once a hot engine is turned off. Don't know why it doesn't happen much with the other Mezger engines, i.e. turbo. Nothing to worry about whatsoever.

 

Sorry, but I would completely disagree with waiting until the oil indicator flashes. Even the Porsche manual indicates a sense of urgency when that low. Granted one bar even two bars below max. is okay, but three and flashing, no way!

FTR, I don't sweat if my .2 3 drops one bar (It did that once). I added less than 1/4 quart when I got home and it went to max. I do agree with someone above who said hot and level is very important. I find this to be true. I have seen an indication if one bar below once warm then full 10 miles later when warmer; each time being apparently level. The full indication would then remain for the rest of the drive.

To the OP, if it was me and I believed I had filled it less than 1/4 over, I'd wait. If more, I'd try to drain some. Just have spare oil in case you drain it all by mistake! Who of us realy knows how much over is too much. In the end we are all guessing. With that said eliminate the possibility of a user error.

So when someone posts that .5 over is no big deal, how do they know that??? I mean we all know that over filling is bad but how much over is too much? If it's not .5, is it 5/8ths, 3/4s, what? We know it's something. Considering that we DON'T know refer to the manual for an absolute.

On a side note, I recently saw a 997 turbo in the Porsche shop for repairs as the owner over filled it. It got into the turbos, cats, manifold, everything else you can think of and more. new parts were needed and were not covered. Don't know how much over (obviously much more than .5 qts.) but something to consider.

 

The typical reasoning behind not overfilling the engine oil on cars with traditional wet-sump lubrication systems is because the crankshaft will aerate the oil within the oil pan and cause overheating and pumping/lubrication issues. Whether our dry sump motors are more or less sensitive (or the same), I don't know exactly.

Normally manufacturers will use a 'safety factor', for lack of a better term, on almost any gage or reading an owner/operator will take to account for things like an operator error. Going slightly above the high mark on a dipstick or calculated oil level reading does not mean imminent catastrophic engine damage. Unfortunately if something can be done incorrectly, it will eventually happen

 

I agree and will say again how much error is acceptable; rhetorical question of course as none of us know the answer. Going slightly over the manufacturer's recommendation is likely okay, it all depends how we and they define "slightly". And, where does "slightly" end???

I am aware of aerating issues with wet sumps. I do not think that applies to a dry sump. My point was and is if we want to guess we can, if we want absolutes go with the owner's manual. With this kind of money tied up in a car I'll go with the latter.

 

Good points, it is certainly always better to be careful and pay attention to what you are doing when working on your car.

I remember the common practice with my E36 M3's was to overfill by .5-1 qt. over the high mark on the dipstick if you are at the track. It somewhat helped prevent starvation issues. That probably came about through word of mouth and passed on knowledge, never from an official source of course.