Originally Posted by Jwmarineuk
Apart from noticing the level decrease in the tank is there any other way I can know the oil an fuel is mixing properly?
The engine will stop suddenly accompanied by a horrible grinding noise!
Joking aside, 2 thoughts here: (as someone who premixes)
1) Premix is messy. If you get even a small spill your deck WILL become a skating rink, and unless you know exactly how much premix has been used, or have a totally dry tank you can never properly guestimate where the level actually is, so will inevitably run over oiled. (which some may argue is no bad thing, but having bought a used engine from someone who thought along those lines & threw in an extra 100ml each time "to be on the safe side", trust me, too much can be a bad thing......
2) My old Suz DT25 had an oil flow switch fitted right by the injection point. It was a wee pressure activated thing held open by the oil flow. That sat in-line on the oil pipe and on "no flow" closed contacts. It was (I believe) wired in parallel to the deadman, as Ipulled the plug & shorted the terminals & the engine stopped dead.
Assuming you have a pump -hose type system, I guess you could retro fit one of these off asn old Suzi and parallel it to your stop circuit. IF your Merc is old enough, there may be a "no run when tilted" mercurey switch - that would be a simple replacement of the mercury (level) switch with the wire from the oil flow sensor.
In some respects (usually wehen filling the tank or doing a lot of slow speed work) I do miss auto mixing......