[HELP] Coolant for the home hobbiest

[f350ca]

I'll have to check the pail I have, didn't think it was a synthetic, I cut it 20 : 1 and have no rust or smell issues. Have to add water to the tanks from time to time as it evaporates. I don't use it much on the lathe due to the huge chip pan thats always full of cuttings, figure I loose a quart or two of coolant that gets sucked up in the swarf and covering the bottom of the pan. Use it all the time on the horizontal band saw and the mill though. Can't remember the last time I changed it in the mill, used it the other day and never noticed a smell but the shop smells like a shop.