Moreover, synthetic motor oils are backward compatible with older engines, and switching from conventional to synthetic does not require an additional break-in period.

Every engine requires oil to function, though oil itself has changed a lot over the decades. It's no longer a bad idea to use synthetic oil in an older engine.

So, what gives? Why are engine oils so thin now? It's not some grand conspiracy or anything, but it is kind of a long and technical answer. The use of thin modern oils comes from a combination of ...