Help with 99 VW Pat oil pan change?

No matter how good you goop silicone, jb weld, or anything else on, if the parts are not clean, it will not hold or stop a leak. I would buy the gasket and use Permatex gasket sealer on it no silicone. That stuff is good and will last a long time. The manual idea is good but if you don't want to do that just remember that you can warp your replacement pan if done incorrectly. Place gasket with Permatex on it to the clean pan and block and install all the bolts to it but do not tighten at this point till all the bolts are in. Then start in the middle of the pan and work your way out in a circle pattern till all are snug. Then go back and tighten (this is where you need the manual for torque specs) to the specific torque for your engine, note over torquing can cause it to leak. Good luck!