I have always used Marvel air tool oil, in plain bearing as well as ball bearing engines. I was told by an engine mfg that any oil that will burn is a good after run and storage oil.
 Also Rislone motor oil is good.

DO NOT   use Risolene, Marvel Mystery, Auto Trans Fluid  etc.. These can cause many problems with some motors, they can swell or destroy seals  ans O Rings, Kill some plastics, and they do not protect as well as proper  After run oils.
Good quality after run oil is easy to get; don’t skip this step.  If you can’t find a good after run at your local hobby shop, there are many available that are made by several companies…then try Prather’s.  They make a good one and so does RJL , Marvel and Aero Products.  Do not use motor oil, Marvel Mystery oil; this is not after run oil.

Marvel makes excellent oil that can be used and as an after run oil and it is available from most auto parts stores and is called Marvel Air Tool oil.  As a matter of fact, most air tool oils can be used as an after run oil; they are designed to fight corrosion in metal air tools and this is exactly what we are looking for.  Another good place to get these types of oils are the large home supply stores like Home Depots and Builders Square type stores.  Look in the department where they carry air compressor and paint guns.  There are many brands of these oils so you see you have no excuse not to use them.

If you want long term storage first flush the engine out with Methanol or WD 40, others use Naptha, the put 5 to 8 drops in the intake, flip over a dozen or so times, repeat, the put several drops in the exhaust, flip over a few times, plug the intake and exhaust with paper towel plugs. the wrap in a dry or oiled cloth, put into zip lock baggie

Randy

Giving it a good shake , so it gets to the wrist pin wouldnt hurt .

Unoiled s/h injuns , its often the wrist pin that corrodes firstest .

I let it sit so the oil goes  to the bottom end, then put the piston up on top center  and hold the head  down, wait a min, the oil will  run into the  piston pin area, the just rotate  back n forth a few times

Randy

   One of the last oils I'd use is Rislone,,,  did that , regreted it.   How bout some Whale Oil ?
                     John

    P. S.  I use air tool oil now 
             because it removes any mystery.

NOT all ATF is a good idea...MOST are Ok to use.

BAD/not so good ATF...generic power steering or auto tyranny oil does have great After Run Oil qualities....BUT beware there are several blends with friction modifiers for the new skool lock up torque converters...these blends are some what abrasive....still usable, but I suspect should be 100% flushed out before running

My preferred is Marvel AIR TOOL OIL...cheap... and it is designed exactly for what we need...inert to most rubber/plastic blends, a lubricant, and hydrophobic...hydroscopic?...well... anyway does not attract or absorb water

Why I prefer Marvel Air Tool Oil

Decades ago, as a mechanic I invested a bit of cash for quality air tools: die grinders, ratchets, impact wrenches, nailers, sanders etc....... I was not set up with auto oilers and thought a spritz of WD40 when using would be OK...WRONG....with long disuse the tool would squeal, and be FUBAR...on disassembly I saw aluminum body to steel part corrosion and rust

I pitched a fit with the manufacture and got a nice gentleman who explained what AIR TOLL is supposed to do...including preserving tools that are used seasonally or infrequently...of course he was hawking his brand, but admitted most all ATO were pretty much same formula.

I got the Marvel Air Tool Oil  at Napa 3 or 4 decades ago. I have some of these tools that sat as much as 15 years without use... not cleaned, not in baggies, just in the bottom of a tool chest drawer ... the prof is a 70,000 to 90,000 RPM die grinder that is as good today as when I bought it from Sears in 1985...only ever fed ATO...and not ATF, 30W, or WD40 or any other lube ( I briefly had used spray white lithium grease)...very bad MoJo...do not use that stuff for any fast rotating parts....door hinges yes...

    The remark about Whale Oil came from way back in High School ,  one of my teachers liked the fact I had a motorcycle & an interest in machinery. He talked about useing Whale Oil several times to me I really never understood his thoughts untill last Winter when Ron Howard brought out a movie about a Whaleing Ship.. I looked up some uses of Whale Oil & saw they put it in ATF  as a friction modifier... 
                 Sick joke , John