Can you use 5W-20 in your 2000 Ford Focus?

Answer 1

The simple answer is yes. The lower the viscosity number (i.e. - 5, in this case) just means that it flows readily at lower temperatures.

An answer from a professional is in order here, this person above was incorrect, You CAN put 5w-20 in your motor, but your motor will likely lose a LOT of engine life, engine's are designed with specific clearances between the bearings and internal components, using a thinner than specified oil Will allow internal parts to rub, or increase friction, the added heat, and likely wear from components now touching the bearing surface rather than floating on a thin layer of oil will cause engine damage, use your manufacturer's recommended engine oil viscosity, most newer vehicles use 5w30, in extreme use or high heat cases you may use a step thicker engine oil, due to the added heat thinning the oil. = 10w30. So for instance if your car was recommended for 5w30 from the manufacturer, but you live in Texas or Arizona, 10w30 is likely in order.