An old Manfrotto 501 tripod head tilt is sticking in one position. Once you apply a lot of force it will jerk free operating normally until it sits for a few minutes then it gets stuck again. I'm sure that the oil must need to be changed.

I thought there was an old thread discussing the type of oil needed, where to buy it and how to dissemble the head, but I can't find it. Has anyone ever tried this procedure?

It's not oil but a grease with the texture of Vaseline. Sorry I can't help with what it is, but that head needs all the help it can get, so it might be worth opening it up and then after cleaning, experiment with various types. The snag with the head is that the start force always seems higher than the moving force, so smooth starts are hard - I wonder if a little less 'stiff' grease would be better, but swapping is a messy and time consuming task.

It's not oil but a grease with the texture of Vaseline. Sorry I can't help with what it is, but that head needs all the help it can get, so it might be worth opening it up and then after cleaning, experiment with various types. The snag with the head is that the start force always seems higher than the moving force, so smooth starts are hard - I wonder if a little less 'stiff' grease would be better, but swapping is a messy and time consuming task.
I actually have plans to replace it because it has a few minor issues with the pan bar.

The main reason I was thinking of rehabilitating it was to sell it so as not to put it in the landfill. Might be easier to give it away for free for parts.

Update: I misspoke 503 instead of 501. Also found out that I don't need to replace the head. The stickiness was due to the combination of two issues. I store my tripod in my trunk for convenience sake as a result it can get very cold in the winter. I also had the resistance set high. When balancing the camera properly, I could reduce the resistance (the camera doesn't have counter balance settings) I haven't tried yet whether I can still leave it in the cold with the lower resistance.

Seems like the thicker consistency of the grease under cold temperature and the restrictive flow of the resistance mechanism caused it to stick.

One final thing I'd like to fix is the pan handle teeth. They're too shallow and smooth which allows it to slip and the bar isn't held tightly enough.

I think a shim might help the bar and then either using a triangle file to try increase the teeth depth or a rubber gasket/washer might give it enough grip so it will not slip.

I’ve got a old libec with a poor serration that lets the pan par move even when really tight. I tried all sorts but the best fix was a circle of shoe leather! I think it squishes between the serrations but lasts a decent length of time. The plastic washer I tried was too hard.

I’ve got a old libec with a poor serration that lets the pan par move even when really tight. I tried all sorts but the best fix was a circle of shoe leather! I think it squishes between the serrations but lasts a decent length of time. The plastic washer I tried was too hard.
Final update: Success! I tried to insert a washer like you suggested then I discovered I couldn't unscrew the pan bar. What had happened is the threads had corroded on the base and tip of the bolt threads preventing in from being loosen or fully tightened. Over a few days I spray it down with w-d and silicone spray and let it sit over night and began to work it free. Today with a help of a wrench I managed to fully unscrew the bolt and lubricate the threads then when I screwed in the bolt it fully tightened holding the arm in place despite the shallow teeth. This is great, I completely rehabilitated a head that I was sure was no good.