It is a 6.5 B&S Quantum engine.
The splitter sat for 2-3 years. The tank was empty, looked dry, and I did not smell foul gas. I was told the guy took very good care of his stuff, so he probably drained the tank or ran it dry; cannot be 100% sure. I put fresh gas in it. It ran pretty good, other than some surging, when I ran the Mystery Oil through it, for about 3 minutes total. It seemed the surging was clearing up at times. When I put real oil in it is when it just quit running.
I will get a new plug. It won't hurt.