Own a lawn mower?

Those skinny oil change bottles are usually 30W non-detergent. Next time you change your oil, get a small bottle and scavenge the little bit that's left over and usually drips out all over the garage floor anyway.

As suggested, I wouldn't worry too much about this. I guess you have found the post about the destructive, galling quality of silicone oil which will ruin an air gun in short order. (UK forum?) If that's so, then there should be a couple of metric tonnes of old leather sealed guns with chewed up compression tubes, etc. At any rate, I use it in my leather sealed guns without losing any sleep. Just don't want to flood the thing if relubing an old seal. A few drops - and that's drops, not squirts - should do it.

Your bit about making it hard to reblue reminded me of something that silicone oil (or furniture polishes) can make difficult and that is refinishing the stock. If it gets into the bare wood it can make it hard to take a stain or finish.

PS - Way back in my Navy daze, we used silicone oil to brighten up the CRSS (corrosion resistant stainless steel) bulkheads (walls) we had in the heads (bathrooms). Would really shine them up for inspection but you didn't want to lean against one or you would go straight down to the deck. (floor)