I add olive oil to almost all my evening meals. On longer trips I use a plastic bottle that I have tested at home to be leak-free. Never had a problem with the right bottle. Oil resupply can be mailed to yourself in sealed plastic pouches (using a heat sealing machine). Have done this many times. Minimus sells 1/2 oz individual packs of extra virgin olive oil that I also like for short trips, though this is a more expensive option.