I have 3 GX CS2 compressors and a boat load of parts for them, and have been doing some testing on a proper grease for both the gearbox and piston sections of the compressor. Here are some observations I've had while testing.
For the piston section, less is more. Renewal Lubricants Food Grade EP grease is my choice. Lightly lube the piston on both sections and the cylinder wall, then a light smear on the cylinder walls, and on the plastic bearing surfaces. Then put a bit in the piston recess to give it a supply to use during running. I also use RL grease on the piston pivot pin as it will migrate to the piston area and there is not mixing of two greases as if you used something else. I also pull that pin every month or so and add grease to it.
Now, for the gearbox, this is the biggest failure complaint of these compressors. The grease from the factory is some sticky stuff, and I've not seen anything like it. That is both good and bad, as it sticks well, but when it's pushed out of the gears, it sticks to the walls and doesn't ever go back on the gear. I found large sections of the gear, completely dry of grease. It migrated to the walls and getting it off was a chore.
My first thought was to use the RL in the gearbox meaning one grease for the whole compressor, but after a couple months, the gear was completely dry, as the grease was squeezed out and no longer lubed at all. No fo for RL.
Next up was regular NLGI #2 auto grease and the result was the same, no go.
I also tried Cornhead gease, as it's a special grease that is designed to stay put, but when heated during running it thins and covers everything. When motion and heat subside, it returns to it's more solid state. Trouble is it migrates too well in a semi closed gear drive and got into the motor section much like the problems encounted with some of the other semi soft greases.
I needed to find a grease somewhere in the middle, tacky, but not so thin it just squeezed out. The greases that came to mind were Lucas Red n Tacky and Green Grease. Both of these greases, when put on your finger are super hard to get off, yet are a creamy texture that will lube well. I tried the Lucas first and it stayed in the gears pretty well and didn't migrate too bad. It's a decent choice. It did not get out of the gearbox at all, so that's a definite plus for it.
Lastly, I tried Green Grease. While I haven't had it in there long enough to conclude it's the best, I did open the gearbox and it looked much like it did when I first added the grease. The teeth were full and the pinion was covered well and none of it migrated to any places it shouln't have. It looks the best so far, it is stringy and clingy and seems to keep lubricating well. I'll have to keep running it as it's only been in there a couple weeks.
I really feel that a few simple maintenance steps with these compressors will keep them running for a long, long time. It is easy to pull the head and check the cylinder walls for lube. I've come to realize that the underside of the head is the best indication of how you're doing. If there's a lot of grease on the head, then you have lubed the piston too much. Obviously, if it's dry, you haven't lubed enough. I try for just a little grease on the underside of the head, and that's just right. Packing the piston recess full of grease was too much, but putting in just a few fingers full was just right.
Regrease the connecting rod pin every month or so and it's looking good. I'm thinking do a full clean regrease once a year would be pretty appropriate and keep the compressor running well. The above mentioned additions of grease and all will be well it looks like.
Also, being stingy with the piston grease keeps it out of the bottom check valve and you won't have problems with building pressure when the gunk migrates to the valve.
These are pretty amazing little compressors and I've yet to have even a piston seal fail, and I maintain my three and another four, some of which get abused pretty well.
For the piston section, less is more. Renewal Lubricants Food Grade EP grease is my choice. Lightly lube the piston on both sections and the cylinder wall, then a light smear on the cylinder walls, and on the plastic bearing surfaces. Then put a bit in the piston recess to give it a supply to use during running. I also use RL grease on the piston pivot pin as it will migrate to the piston area and there is not mixing of two greases as if you used something else. I also pull that pin every month or so and add grease to it.
Now, for the gearbox, this is the biggest failure complaint of these compressors. The grease from the factory is some sticky stuff, and I've not seen anything like it. That is both good and bad, as it sticks well, but when it's pushed out of the gears, it sticks to the walls and doesn't ever go back on the gear. I found large sections of the gear, completely dry of grease. It migrated to the walls and getting it off was a chore.
My first thought was to use the RL in the gearbox meaning one grease for the whole compressor, but after a couple months, the gear was completely dry, as the grease was squeezed out and no longer lubed at all. No fo for RL.
Next up was regular NLGI #2 auto grease and the result was the same, no go.
I also tried Cornhead gease, as it's a special grease that is designed to stay put, but when heated during running it thins and covers everything. When motion and heat subside, it returns to it's more solid state. Trouble is it migrates too well in a semi closed gear drive and got into the motor section much like the problems encounted with some of the other semi soft greases.
I needed to find a grease somewhere in the middle, tacky, but not so thin it just squeezed out. The greases that came to mind were Lucas Red n Tacky and Green Grease. Both of these greases, when put on your finger are super hard to get off, yet are a creamy texture that will lube well. I tried the Lucas first and it stayed in the gears pretty well and didn't migrate too bad. It's a decent choice. It did not get out of the gearbox at all, so that's a definite plus for it.
Lastly, I tried Green Grease. While I haven't had it in there long enough to conclude it's the best, I did open the gearbox and it looked much like it did when I first added the grease. The teeth were full and the pinion was covered well and none of it migrated to any places it shouln't have. It looks the best so far, it is stringy and clingy and seems to keep lubricating well. I'll have to keep running it as it's only been in there a couple weeks.
I really feel that a few simple maintenance steps with these compressors will keep them running for a long, long time. It is easy to pull the head and check the cylinder walls for lube. I've come to realize that the underside of the head is the best indication of how you're doing. If there's a lot of grease on the head, then you have lubed the piston too much. Obviously, if it's dry, you haven't lubed enough. I try for just a little grease on the underside of the head, and that's just right. Packing the piston recess full of grease was too much, but putting in just a few fingers full was just right.
Regrease the connecting rod pin every month or so and it's looking good. I'm thinking do a full clean regrease once a year would be pretty appropriate and keep the compressor running well. The above mentioned additions of grease and all will be well it looks like.
Also, being stingy with the piston grease keeps it out of the bottom check valve and you won't have problems with building pressure when the gunk migrates to the valve.
These are pretty amazing little compressors and I've yet to have even a piston seal fail, and I maintain my three and another four, some of which get abused pretty well.
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