Q: What will happen if I mistakenly put in 5W-30 in my engine instead of what the manual calls for – 5W-20? Will it cause damage?
A: The difference between 5W-30 and 5W-20 is the viscosity (thickness). Many new cars now recommend 5W-20 to be used all year long. While others, indicate that it is OK to use 5W-30 in warm climates. The lower viscosity (5W-20) is used to circulate the oil quickly throughout the engine when the engine is cold. Check your owner’s manual and see if the manufacturer allows the use of 5W-30 during warmer climatic conditions. The correct viscosity of oil should be used so that the warranty will not be void.