m44 fuel line o-rings
 

So, I had to pull the intake and fuel rail on my 318ti after a coolant fitting broke. When I pulled the fuel rail the o-rings on the fuel lines just fell off. They don't look like typical o-rings, they are concave in shape. I can't find them anywhere at the parts stores. Is it really important that they're shaped like this or can I just replace with some typical round o-rings?

Don't chance it, replace them with the factory ones.

Only problem is I can't find any.

I can find plenty of your standard o-rings like there are on the fuel injectors but none of these concave shaped ones. At this point I'm just going to have to try it with a standard o-rings and see if it leaks.