Use cooking or salad oil for lubricating non-essential mechanical things like hinges, tools, etc. Always use a light coat of oil, as that will keep the tools from rusting. Hence there is no need for you to buy expensive and toxic chemicals.
Use a product, which contains phosphoric acid to clean tubs and showers. Scrubbing can make the surface rough. So to the tubs and to keep it smooth remember to use the chemical.