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Vin: It is the difference between a manufacturing environment, and a service repair shop environment ;) Don't sweat it.

Core plugs, as you noted, are a result of the casting process. If they cover an oil galley, they are called galley plugs. If they cover the water jacket, they are often, and somewhat inaccurately, called freeze plugs or frost plugs. They can push out when the coolant freezes. However, they aren't all really designed to protect the block as is sometimes assumed, they simply push out in reaction to the frozen coolant. The block can still crack.

This went off track when the galley plug was referred to as a freeze plug. Freeze plugs won't cause an oil leak, they will cause a coolant leak. Galley plugs can be the source of an oil leak. Also, galley plugs don't have to be push-in plugs like core plugs, they can be screwed in. The plugs are sometimes removed to install oil lines, ie for a turbo lube system or gauge.

All of the above is based on general mechanical repair knowledge, not on specific knowledge of the BMW engine. Purists are welcome to correct me.

Jeff

That makes perfect sense. Thanks for the clarification. :thumbup:

OK UPDATE!!!!!

This is what is going on with my car. First off JCL you were right. My problem is the crank-shaft seal? and a check valve O ring. The problem is minor and will be done today. I told them to keep it another night just to drive it around and make sure that there is no more leaks. All covered under warranty. I believe this happened as JCL said, when I had my oil sep. crack that one below zero night. It must have done a lot of damage to almost all my seals. I had to replace the following. Oil sep., all breather hoses, valve covers gaskets, rear main seal, and finally the above items. Talk about a problem!!!! But good news is everything has been covered under warranty, thank GOD!!!! I have one question. When do my spark plugs need to be changed??? Since I've done all this work to my car, might as well get that done also. Thanks...