Read the manual 80's engines run 10W-30 or 10W-40. You will hear a lot of advice about some "super oils" ... or the best oil. Buy what YOU like.
Just stick with conventional oil, I would go with a 10W30 in the winter and then switch to a 10W40 in the summer, keep an eye on the oil, sorry to say but the little rampages were known to use some oil when they got some mileage on them.
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