DeOxit F100L is the oil I used.
Contact cleaner (i.e. Deoxit D100): no lubrication, will strip the lubrication out of controls and make them feel bad and wear faster. Clears out dirt and oxidization pretty well, especially if you follow it up with canned air.
Control cleaner (i.e. DeOxit D5): contact cleaner + lubrication. Works fine for routine potentiometer cleaning, not necessarily good for encoders. Will mess up jacks and some kinds of switches because dust will stick to the oil they leave behind
Electronic oil (i.e. FaderLube): just the oil from contact cleaner. Using contact cleaner to clean pots and then manually relubricating them can work better than just using control cleaner if they’re really dirty. Theoretically a common off the shelf oil like 3-in-1 can have some resistance and make the potentiometer not work as well but I don’t know how true that is.
There are also electronic-safe greases but they don’t really spread around on their own so the best way to use them is to actually open up a fader and manually apply the grease to the inside of the cover, so the entire sliding part gets lubricated. I haven’t bothered to do that to anything yet.
Encoders are mechanically different from potentiometers as you know, so cleaning them isn’t really the same as pots. You’ve already done the hard part. When I did the s5000 encoder, after I cleaned it I put a little bit of FaderLube on a cotton swap and carefully wiped it onto the conductive plastic wheel and friction points. I didn’t drip it in or anything, just a very thin coat like what was there before I cleaned it.
EDIT: the DeOxit ubricant is pretty thin, like sewing machine oil, so the encoder still might not have the same feel as it did before you cleaned it. The one I did on the S5000 has strong detents but very little friction so the FaderLube was just right in that case. I haven’t used a MKII but the MKI Octatrack encoders have some resistance, so something a little thicker might actually work better.
