Filling crank case with too much oil will cause them to leak too. Quick change places are notorious for this since a stock VW takes only 2.5 quarts of oil. Most seem to want to fill it with 4 or even 5 quarts! Just remember an extended sump, remote oil cooler and remote oil filter do add to capacity. Too much oil gets whipped up by crank shaft and also builds up crank case pressures (blow by) forcing oil past seals and push rod tube.
Valvoline™ VR1 Racing Oil should be available locally at Advance, Autozone, O'Reillys. It had the desired high zinc content for flat tappet applications. It's available in SAE 30 weight (what VW specified way back), SAE 40 (for worn engines, leakers or hot summer apps) and 10W30.