1993 Nissan 240SX Low Compression Questions

Hello, I own a 1993 Nissan 240SX w/168,000 original miles. I purchased the car new and know that the car/engine have not been abused.

I've noted (for a few years now) that the cylinder 2 spark has oil - not only on the pug tip area, but also on the base of the plug. The other 3 plugs look good.

I ran a compression test (following Nissan manual guidance) and came up with very low results:

Cylinder - PSI - PSI after adding a little oil
1 - 110 - 135
2 - 105 - 130
3 - 105 - 115
4 - 110 - 130

The Nissan (1993) manual says that PSI should be 179, minimum - 151, and max difference between cylinders - 14.

The car runs fine - no stumbling, missing, etc. It burns/loses virtually no oil. Performance may be down somewhat - but it is not significant. (I drive the car mostly in town, drive the speed limit, no jack-rabbit starts, etc, and as the car has aged - so have I - not "Speed Racer" or the like.)

My questions are:

1. How concerned should I be about the abnormally low compression?

(My goal is to continue to own/drive the car sensibly - without experiencing serious mechanical issues.)

2. If the cylinders continue to lose compression (over the next several months/years) - what symptoms/issues will I most likely experience with the car?

3. Outside of pulling apart/rebuilding the engine/head - are their any additives/products you would recommend I look into to help restore (some) lost compression?

I've seen various products at the auto store advertising their ability to restore lost compression, etc, though I confess to being a skeptic.

Thank you,
Mark McKamey
Mark. McKamey@us. Army. Mil