Hey all, I post this to be shot down. Tell me if I’m wrong.
I’ve owned 2 cycle outboards off and on for over 30 years. All Evinrude and Johnson. The few problems I ever had with them were related to the outdrive (once, for age) or were electrical (periodic, for submersion in saltwater). At a marina, most places will put it in last. When refilling a partially full tank, it is hard to know how much Evinrude oil to put in until you know how much gas you put in.
Personally, I’ve added the oil first and last. First for empty tanks, last for partials. The oil is completely soluble in gasoline and will naturally disburse in a short period of time.
This may be a bit dated, but the anecdote is that oil injections systems and their alarms may fail. The downside is your engine will overheat and you will sputter to a stop. The upside, when working properly (which is usual), is that they do accurately apply the correct amout of oil, which reduces smoking, polution and possibly oil usage.
On the occasions where I or someone (the guy at the marina) forgot the oil, we sputtered to a stop, deliberated, divined the error and added the oil. Then we resumed our fun. On the occasions where I or someone (it was me) doubled the oil, we smoked quite a bit until our next tank.
I don’t recommend forgetting the oil or accidently doubling it, but if on rare occasions it happens, it is not catastrophic.
If you, someone else or the oil injector messes up often, it probably could be.
My suggestion is to use the oil injection system and periodically give the oil level a visual inspection during use. It may be hard to tell with light usage, but over time you will be able to tell. If you sputter to a stop and the oil isn’t being used, put oil in the gas.
The absolute here is to always keep a quart or two of the 2 cycle engine oil on the boat.