[Jbetschart]

I have a 94 that is new to me and thought I would change the plugs in it. Its a Merc 350 Z212.

Do I really need Marine plugs or will auto plugs do just fine.

Is there anything I need to look for when I switch them out?

Or it the spacing that counts. Same as current installed.

Thanks

[Tom]

A spark plug is a spark plug. I used regular auomotive without issue. You want to make sure your plug wires are good and not letting any errant spark loose as that could be problematic. I would hope marine wires have extra insulation and larger boots than automotive, but I've never compared them.

[Captain Steve]

Marine plugs are stainless steel. Automotive plugs are not.

[MAJIC]

There was a pretty good thread about this: spark plugs

Upshot - non-marine are OK if you change them frequently. Marine plugs are stainless and won't erode as quickly. Wires are extra insulated with better connections. Yes car engine compartments take a lot more weather exposure, but electrolysis, etc with the boat sitting in water (especially salt) wreaks havoc...