Oil leak

I had a bit of an oil leak yesterday. I got onto the motorway, and suddenly I had a huge cloud of white smoke behind me. :( I knew it must have been oil on the exhaust, so I turned round and headed home, keeping an eye on the oil pressure gauge. At one point it started to dip a little so I stopped and topped it up with oil again.

Anyway, the cause was this:



As you can see the gasket decided it wanted to be the wrong shape, and oil escaped out from under it. So now with a new gasket it should be ok. I have used a new rocker cover clip too, just in case. Not sure if this was the cause or not, but at some point in my rocker cover's life, someone used a silicone sealant on it. That's stupid for two reasons, one its quite slippery and might cause the gasket to move out of position (did that happen here?), and two, bits of it might end up in the oil system which is not good (although they will be filtered out). Anyway I cleaned it all off. NO sealant should be used at all, only good gaskets and clips, and clean dry sealing faces.