From the linked article, this is the key sentence:
''VI Improvers are polymer material that expands as the oil warms up.This does NOT thicken the oil as is often stated.It merely slows down the rate at which oil thins out as the temperature rises.''
But thin (with heat) it does.
''VI Improvers are polymer material that expands as the oil warms up.This does NOT thicken the oil as is often stated.It merely slows down the rate at which oil thins out as the temperature rises.''
But thin (with heat) it does.
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