How do bearing clearances effect what type of motor oil you need?
The tighter the clearances the more you need an oil that is thinner at operating temperature. Some newer cars have tighter clearances that require the use of 5W-20 oil. Similarly if the clearances are relatively large or the bearings are worn you may need a thicker oil like 10W-40 or 20W-50. When making judgments on what kind of oil to use, look at the second number because that indicates the oil’s viscosity at operating temperature.
