Can you use cooking oil to loosen a stuck water supply valve?

Yes, you can use cooking oil to help loosen a stuck water supply valve. The oil acts as a lubricant, potentially breaking down any rust or mineral buildup that may be causing the valve to stick. Simply apply a small amount of cooking oil to the valve and give it some time to penetrate before attempting to turn it again. However, if the valve remains stuck, other methods or professional assistance may be necessary.