Early last week, my daughter informed me that the oil light came on in her car. I tell her to stop driving it (she was at home) and check the oil. As expected, it's below the minimum. We need to do an oil change anyway, so I tell her that I'll stop and get her some oil on my way home. But she and her mom had some errands to run, so they take the truck and on their way home, stop and buy supplies. When they get home, my daughter takes the initiative and tops off the oil so she has use of her car until we can do the oil change.

Saturday finally rolls around and I'm itching to get the oil change done but the ladies need to run more errands. On Saturday afternoon, they finally get home and inform me that the Outback isn't running right. My daughter tells me it hasn't been running right since she added oil.
Oh, no.
At this point I'm wonder where things might have gone wrong. Did she put the oil in the wrong spot? Wouldn't the oil light have stayed on if she had? Did she run it too long with the oil light on and burn up something? Inquiring fathers want to know!
So, I did the only thing I could and went outside to check the oil myself. I discovered that she added oil into the right place, but she added too much oil and it was over full.
To the uninformed, this may have seemed like No Big Deal (TM), but I'm here to inform you that it is a Really Big Deal (TM). The dealer adding too much oil is exactly how I ended up with a new engine in my WRX. When the oil level is too high, the crankshaft gleefully splashes around in what was once a shower but has become a kiddie pool.
The splashing turns the oil into foam, much like whisking oil and egg together to make mayonnaise. The poor little oil pump can't move air, so it stops delivering oil to those critical moving parts. They overheat and start disintegrating. Next thing you hear is a whole lot of tapping coming from your once pristine engine.
So, I do the right thing and call my daughter outside to take a look for herself. I tell her to check the oil and tell me what she sees. She recognized her mistake immediately. I ask her to go get the jug of oil so we can see how much she added. Two and a half quarts. Whoops.
Now we don't have enough oil to do the oil change. We also discover that she bought two different weights, one 5-quart jug of 0w-20 and two one quart containers of 5w-30. Cue another conversation about getting the right oil and she is completely confused. I'm telling her to buy one weight, "the car" is telling her to buy another. We discover that someone switched the oil cap for the one off a 2.5L which specifies 0w-20, not the correct weight of 5w-30. Thanks Subaru techs. You screwed it up again.
So, we take a trip to the Zone of Autos and buy some more. I show her again how to look up all of the part numbers and quantities and we get our supplies.
The next morning, we went about changing the oil. It's an oil change. Nothing new here. The only thing we did differently was have a conversation about knowing how much the car holds, how much oil it may retain, and how to sneak up on the right oil level.
On the post-oil change test drive, the engine was back to normal. Crisis averted. All is well once again. Now to address the rattle coming from the back....