But grease as a noun would only apply to mechanisms for us

Just backtracking here a bit, fisk - because re-reading your post has got me (half-)remembering the Shakespeare line about "Greasy Joan doth keel the pot..". Can't get much more this second, apart from Marion's nose being red and raw - but I realised this stuck way back in childhood for me as an image of grease = yuk for food. Of such fragments whole language edifices are built...?