[Itwrx]

I have a 1994 4.3 Merc. Hours unknown. I was debating on outing in a oil additive. Maybe Lucas or Z-Max? I know it’s a flat tapped lifter and someone recommended adding Zinc (Lucas break in oil) every oil change. I have only ran quicksilver marine oil in it to date. Thoughts?

[pole trick]

If you running as prescribed by manual mercury oil you should be fine. Shouldn't need any snake oils...one of the few additives that I found that works is seafoam and the mercury stuff as needed.
Having it propped right and good fuel and correct oils and checking fluids and gauges Is key in i/o long life.