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- - spark plugs (http://www.mariahownersclub.com/forum/original-mariah-talk/3690-spark-plugs.html)

Hi folks!Hope everyone is well in "Mariah-land".Question is this-How often or how many hours before replacing spark plugs on 5.7 EFI merc?What plug works best?Are the aftermarket hi performance plugs better?Nowadays cars & trucks seem to run forever without changing plugs.Thanks

I have the original plugs in my 1995 4.3L. No problems. You really don't put a lot of hours on a boat engine compared to an auto.

Sounds reasonable.Would hi-performance plugs make any improvements on performance?

I think you need to use marine specific plugs (you know, just like the regular part, except it has "marine" on the package and a price tag 4X higher?!?!? :punch_out: ). Seriously though, I think there is a reason, but I can't remember right now. If that's the case, there probably isn't much of a "performance" choice out there. I'll do some more research...

These are engines. How you "drive" the engine does determine the spark plug life. Unless you have platinum plugs, you do have to replace them, especially if you do a lot of idling, stop and go, etc. Think of a car in traffic, versus a car running on the highway.

I pretty much follow the 200 hour tune-up guide as I tend to do about 50% cruising and 50% stop and go (tubing, skiing, fishing, trolling, etc).

They get fouled, do breakdown, etc. There are marine grade plugs - stainless, etc. I'm not sure about performance based.

I replaced the plugs in an 1988 Merc. 5.0L engine. I don't know how old they were when I bought the boat, but they looked like a normal wear and tear on a 12,000 mile plug from an engine.

So... for the cost, the performance and economy gain are worth it. Don't forget the rest of the tune-up stuff, including filters! Is platinum worth it??? That's your call based on amount of usage and how you use it.

IMHO...:)

Hi guys, Found this site on the Google, thought you would be interested if you like NGK plugs.
Contact NGK Spark Plugs
Only 10 more weeks til I get the boat out, it's killin me.