Agree. But can only imagine it’s been disconnected after it’s went pre mix at some point. Worry currently might be that current owner isn’t aware of it and not pre mixing ?I would imagine if you had a helm position with remotes then the oil tank wires would connect via a wiring loom to a buzzer or light in or by the remotes.
If tiller steered then your more likely to keep an eye on oil level so no buzzer.
Any failure of the oil tank such as pipe blockage or valve failure leads to a seized engine.
Can't go wrong premixing the fuel.