Regarding mayonnaise; when I hear of a "household item" solution like this, I think, okay, what is it in the item (mayonnaise in this case) that is the active ingredient. So, for the mayo, is it the oil? The vinegar? Isolating the active ingredient and then just using it can be a much more efficient way of doing it. Honestly, not that it is a big deal to use up some mayo on your sewing machine - but in general, I think it is better to know what it is you're after, and use just that thing.
I think, based on what others here are saying, that in the case of the mayo, it is the oil that you want to isolate.
I think of people buying a cleaning product for $5.00, with the magic syllables 'oxy' in it... and guess what? Probably fifty cents' worth of peroxide would have done the task.
Just my cheapskate's $.02 worth. But SMR, I'm not criticizing your suggestion - it is quite interesting to me, actually! :-)