Cons of putting too much oil in the engine
 

So I am checking my oil level in my 8 and notice that it is a tad low so I go ahead and put some oil except I put a lil mo than needed. (1cm above full mark)

But after that the engine sounded very nice and car drove very smoothly. However the next day when I check it again the level was back to the full mark.

SO my question is. Is the excess oil being dumped into the cat and is it going to damage the cat over time?

Or putting a lil more than needed is ok ?

I'm no expert, but I've read that many dealers tend to overfill a little on oil changes. (Mine does, and they're one of the few Mazda dealers with a service dept. people actually like.) So I'm pretty sure it's no big deal.

bt did you notice if your car drove smoother than it already is?

Don't notice a change. Smooth before, smooth after.

Oil is injected accordingly to rpm therefore I doubt there's much left to stay in the cat. Oil expands as temperature increase therefore it causes fluctuation in oil level sometimes. My dealer and I had one time or another added 1 litre more of oil after full mark, luckily for me nothing ever happened but some other owners reported oil sokaed air filter.

I have been wondering the same thing my self. My cars pattern have been to put half a liter every 1k miles. After an oil change i checked the oil after 1000 miles and it was still full. I thought no biggy. After 2k miles, I checked again, and noticed that it was still full.

I went to the service department and told them that the oil was over filled after 2k. From my experience they had to atleast put in an extra quart. The tech guy promise me that there was no reason to worry and that it is ok.

I ask them about possible oil geting on the air filter and was told that would no way happen. Oh yeah, after that he told to get that stuff i am reading on the internet out of my head after he asked where I heard of this.

I tried to check my air filter, but still having trouble getting the freaking air box off. Im gonna have to check the DIY section

disconnect the accordion thing, then yank the back of the air box straight out.
THen you can undo the clips and open the air box

You can try to fanagle it without doing that.. but this way is MUCH easier.