St Jack thanks for an interesting contribution but I wonder if you aren't being a touch over cautious here. Firstly I have some doubts that modern oils need to be shaken to mix up the additives. The whole point of additives is they are in solution in the oil not a sludge at the bottom surely? Can you substantiate your view?
I'm also surprised at the assertion that engine failure have been traced to oil can debris. Debris perhaps, but specific to oil cans? Really? Oil cans are made from rolled sheet which is in a heat treated state to be soft rather than brittle. The action of piercing it tears the metal rather than splintering it, and provided it is done with a single action there should be nothing to generate swarf.
Your suggestion for using a purpose designed can opener is a good one, we can certainly agree on that. And something that avoids the situation of not being able to open a beer bottle/can if normal methods fail as well!
