Rod Knock

Just got my 2000 Sportage repaired. Spark plug had come out of the head and rocketed up through the coil. Replaced damage coil wire and pllug. Compression and blowdown test were fine, however they are now saying the engine does have a slight rod knock. This seems a little odd for an engine w/ 37,000 miles. Does anyone have a similar experience or information on this sort of problem. The vehicle is only used for commuting the better half to work so I'm going to run it. Is there any additive/oil combinations that could possible\y extend the inevitable failure. The dealer also said the a failure would likely require an entire engine replacement. Whatever happened to replacing the connecting rod, wrist pin, cylinder, main bearing and caps and machining the crank and if needed a cylinder bore?

Thanks

I highly doubt you have a rod knock. What the mechanics are probably hearing is piston slap. This is a normal condition in the DOHC engine. And there are no additives that will get rid of it.

I highly doubt you have a rod knock. What the mechanics are probably hearing is piston slap. This is a normal condition in the DOHC engine. And there are no additives that will get rid of it.
Thanks, That's a bit of relief. It sounded suspicious to me also.