Your engine has channels in it for the oil to travel if it is too thick it wont distribute properly and over time it will cause excessive wear to parts that would normally last much longer. It also creates greater oil PRESSURE which puts more pressure on seals gaskets bearings and all other engine parts over long periods of time in daily driving and high mileage situations it isnt good for your engine. 20 w 50 race oil was meant for what it says ,a race. Lots of newer engines have failed due to running the wrong weight of oil and very restrictive oil filters such as a fram on the Ford 5.4. The oil filter bieng too restrictive coupled with too heavy of an oil that wont get up to the top end efficiantly for all of the variable cam timing and other high tech engine components. So moral of the story no matter what oil you choose to run in your ride make sure you run the viscosity that the owners manual says to run.
