As another person said, white lithium grease. I think that is what the oarlock mfgr's recommend. Waterproof and stays in place. I put it on twice a year, and haven't had a problem with it getting on tubes. Perhaps the washers I use above and below the oarlock shaft hole on the stand, help keep it in? I'm not sure, but so far, so good. And my boat is yellow, so I think I'd notice!
I am a river, babe - I've got plenty of time, I don't know where I'm going, I'm just following the lines..... - "We are water" by Shaye