CustomSteel

I know this is a couple of months old, but I have the same freewheel and worked on it at the same time as you were asking this. It was a bit sticky, as one would expect from it's age. I simply flushed it clean with WD-40 until everything freed up properly, and afterwards flushed and lubricated it with Tri-Flow. It works like a charm, and sounds pretty nice when coasting as well. I haven't had any issues with it since.

OldRoadman

I have rebuilt a number of Suntour freewheels and it is not east the first time. What works just as well is to just soak it in mineral spirits over night, remove and let it air dry until it's free of solvent. The best lubricant I have found with the best viscosity is 30W non-detergent oil (good for pawls and the bearing races). Drizzle it into the access points on the freewheel. Spin it until you hear the change from the lubrication. Just re-lub. from time to time and you should be good for years.

PJB1

I realize this thread is very old, but I wanted to add something that might be helpful in case someone is trying to repair a freewheel and happens upon this thread.

Back in the late 60's & early 70's I would trash pick bikes and fix them up, including the occasional freewheel rebuild. It really isn't terribly scary if you're methodical about disassembling it.

If you open it, I recommend doing it inside a baking tray and drawing an exploded view of every part as it is disassembled. (I guess now-a-days one can photograph them.)

But, if you don't take it apart and solvent clean it assembled, it is Very Important when you are finished to tighten the locking ring that holds the freewheel together. (That's the part with the two dimples for a pin wrench. It is Left Hand Threaded.) You can use a pin spanner or a roll pin punch & hammer. I learned this the hard way many years ago and received a very timely reminder today.

I trash picked a bike that was at the next door neighbor's house for over 3 years laying in the dirt, snow, rain and general bad-for-bikes-stuff. They threw it away and I snagged it. The chain was seized to the cogset and the cogset was frozen on the freewheel. When I got all that extracted, I decided not to take apart the freewheel unless I had to. I flushed the freewheel to free up the pawls. After letting it dry and lubricating it I was a happy guy.
Until the Inaugural Test Ride this evening....

About a mile into the ride, I began hearing a clunk-clunk-clunk while pedaling and back pedaling. I Fred Flintstoned the bike back home and put it on the stand. I removed the rear wheel only to find that the freewheel's body (the part with the pawls) had unscrewed itself from it's locking ring. I guess that's one way to disassemble a freewheel.

I believe all the cleaning and lubricating removed whatever force was holding the freewheel parts threaded together, allowing them to unscrew while riding.

I got very lucky that the bearings were in races and the c-spring didn't get caught & broken; so clean-up, lube and re-assembly was super simple.

In the old days, I'd de-grease the threads & use oil paint or nail polish to lock the locking ring's threads to the body. Today, we have removable thread locker available. (Usually it's the blue kind.) I recommend using it on that ring while you tighten it (Reminder- Left Hand Threads).

So, all the above million words are meant to say:
Please tighten the locking ring if you solvent flush and oil the freewheel while assembled.

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And, If I may be pretentious and add an unsolicited opinion of what I used for lubrication...
For the freewheel today I used Synco Super Lube synthetic on the balls and races. For the pawl pivots, I used LPS 3 oil. I've never tried these on a bicycle, so this is an experiment. (As a kid, I used to grease the balls with whatever I could scrounge up. For oil, I pull the dip stick from my father's car and let it drip onto the pawls.)

For chains, as others have mentioned, I also believe that there is no reasonable way to get home-applied dripped or sprayed oil into all the tiny passages. Here's the old-guy method I still use if I have no alternative but to remove the old lubricant:

If I must de-grease a chain, like on a super rusted one, I'll dunk it in a tray of solvent of any safe & no residue type and change the solvent until the bath is perfectly clean. I prefer water based and without phosphates. Lemon juice works great, but a bit expensive. In a pinch, mineral spirits works. Lacquer thinner works, but is kind of scary for brain cells and the earth. You can save the used solvent for future de-greasing projects.

Next I will wash the chain to within an inch of its life, usually by boiling in water with dish machine soap. Then I alcohol wash the chain until the rinse is ultra clean of soap.

Next it must dry completely. You have to rush this in the warm oven or the chain will promptly begin to rust.

While the chain is drying in the oven, I melt simple canning paraffin (or dollar store candles) in a double boiler and immerse the chain and leave it until no more bubbles appear. (10 or so minutes) As an extra (overkill) step- the jar I use has a flare fitting in the cap, so I put the cap on and use my vacuum pump to draw out all the air. This will force the liquid wax into all the tiny places. I then hang it over a paper so it can drip while the wax solidifies.

The chain will be stiff when removed & cool. A little flexing will solve that. Be sure to remove the oil from the cogs, derailleur wheels and chain ring. Wax from the chain will coat these as the bike is used. And, do the test cranking over newspaper or something you don't care about because some wax chips will be set free. I've done this for years and never have to oil a chain again. The wax lasts many years before it needs to be re-applied. The best part is that dirt doesn't stick to the chain or cogs.

I'm no bike pro, just someone who learned while a broke kid.
Hope this helps some one someday enjoy working on their bicycles!