Had to go for a drive to relatives yesterday (to change brake pads and some other minor things to the sub). I checked oil and added a little bit since i am planning on changing it in a few days. After driving 150 miles and arrived a my destination opened the hood to undo the brakefluid container i was missing something Big an Yellow. Apperently i drove the whole way without the cap. Luckily it was nice warm weather with no rain and no dust. Not too much oil was spilled in the egine bay just some droplets.

Is it really bad to drive without the cap, it seems like there is an overpresure from the pipe when i covered it with some plastic for the road back.

You aren't going to hurt anything by doing that. Having some pressure in the crankcase is normal. Just get a new cap and clean up any oil spots.

Had to go for a drive to relatives yesterday (to change brake pads and some other minor things to the sub). I checked oil and added a little bit since i am planning on changing it in a few days. After driving 150 miles and arrived a my destination opened the hood to undo the brakefluid container i was missing something Big an Yellow. Apperently i drove the whole way without the cap. Luckily it was nice warm weather with no rain and no dust. Not too much oil was spilled in the egine bay just some droplets.

Given the circumstances you've described, I wouldn't be concerned.

 

 

Is it really bad to drive without the cap, it seems like there is an overpresure from the pipe when i covered it with some plastic for the road back.

Engine blow-by will somewhat pressurize the crankcase. The PCV system will alleviate the pressure to some degree, but at idle the PCV valve isn't open much. Nevertheless, you could check that the valve and hose are not obstructed.

Hate to admit it, but I did this years ago with my 88 Honda. The filler cap sits on the valve cover there. I drove about 4 hours. The next day, I noticed the oil mess on the front of the car and some dripping on the ground. I was at the add mark. Lost a liter of oil. Years later, seemed no harm was done.

 

Commuter

I did this once in my Fiat 124 Spider. Didn't get very far before I had fairly major smoke coming from under the hood! No damage, just lost a litre or so onto the exhaust manifold.

Good thing there is still a tube of 10 inches just lost few drops

I wouldn't worry about engine damage, either. I would at least think about replacing the PCV valve, though, just in case it's not working quite as well as it should be.

an engine fire can result from the oil filler cap being left off. call the fire department to confirm that if you don't believe me. (i've seen it). the interesting thing is that fires can start after the car is shut off as well. the oil is all over the engine/exhaust. once the car is shut off the cooling system is not operating and the internal heat of the engine starts to disipate outwards and the outside/surface temps can start to rise. if there's something that can ignite and it gets hot enough it could happen. then if that oil gets hot enough to burn...that's how it was explained to me.