Apologies for a long one
I'm assuming that it hasn't been just me watching the hour meter climb and wondering whether, "Have I been greasing enough, or over greasing?" Or, "Does my connecting rod still have grease?"
Well I figured I'd find out since no one has post anything about a long term PM check and show what was found.
As can be seen every bit of the grease was black. I concluded that the coloration is probably just minuit o-ring wear particulars since none of the grease had any hint of unusual/burnt smell. Rub an o-ring with some sand paper, even 2000 grit, and it's like graphite powder turning everything black. And even a little would a long way when mixed with clear grease. (Correct me if I'm wrong.)
Wasn't surprised to find water in the piston since I'm in a high humidity environment and always blowing water out the bleeder.
My apologies for not taking pics of second stage cylinder o-ring arrangement. Thought I did. It was pretty gunky though as can be seen by the base and inner cylinder.
The final stage piston rod looked awful as you can seen. I'm now leaning towards believing that I've possible over greased at some point. However there's nothing that I've found anywhere to give it any sort of comparison with after long term use.
Despite all appearances I've probably lost 3 to 4 seconds max off dead head test from new.
Following the Jason S video off YT, disassembly and reassembly isn't difficult. But there nothing about replacing anything other than a vague cleaning of the piston rod (I opted not to try that). He's simply pulling a new apart and sliding it back together.
The rebuild kit that comes with compressor, or can be purchased, isn't nearly adequate enough. There's little springs, check valve balls, and o-rings they should have included. Drop one, or damage one and You Are Screwed. On that note I only replaced the large inner piston o-ring included with the kit (rounded edges were obviously flattened off), and did it cautiously because there's hidden springs underneath the lower plastic ring. The larger cylinder o-rings should also be included just for general principal replacement after disassembly.
Also not included are the bonded sealing washer (Dowty Seals) for the pressure lines. One of mine blew when pressure testing after reassembly. I've ordered some that hopefully should work. Mean while I did a temporary make work thing I wouldn't recommend, so not describing.
Did a mild greasing of moving o-rings during assembly, and gave knob 1/2 turn when running. Stationary sealing o-rings I lubed generously to insure a seal since no way to replace them.
Final results are that I'm simply back at my original out of the box dead head. For all the effort, cost of buying new bonded seals, and trepidation of screwing up what didn't have parts to fix, gaining back 3 or 4 seconds of dead head wasn't worth it.
So my opinion is go light on the grease, and just run them till they quit.
If everything single thing possibly needed was in a rebuild kit I might say otherwise. And then only recommend it being done by someone with mechanical abilities and patience to deal with tiny parts.
Also the connecting rod has uncaged roller bearings, slip those all the way out and you'll have a very unpleasant day. It does appear that they've stayed lubricated though.
Hope the was helpful