• It’s a DIY world, but here’s one task you should leave to the professionals: changing your car’s oil. If you do it yourself and have a spill, the used oil can contaminate up to 1 million gallons of fresh water. Motor oil is insoluble, contains heavy metals and is very slow to biodegrade. Even trace amounts (undetectable to the eye) are enough to make water unsafe. By taking your car to a trained…