I just had the exact same problem in mine. I switched to mobil 5w-30 yesterday and the noise is all but gone. I'm guessing it was a lifter. I heard a VERY SLIGHT ticking for a couple of seconds today when I cranked it, but after that nothing. Certainly not like it was before I changed it.

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Married men live longer than single men do, but married men are a lot more willing to die.