If you go that way, I'd get some octane boost.

A few years back I put mid-grade 89 in my Buick.

A week of that and I spent $400 on a harmonic balancer.

Ethanol is widely used in Europe as here. Our engines are designed for it. I agree with Bri3d and would probably use an additive if the car sits.

At least ethanol is not a carcinogen if it gets into local groundwater, unlike MTBE