As mentined by the members befor it seems like your fan might be blocked/hindered or that your timing might be off, leading to the car running hotter (try to check the plugs for tell tale signs).
Believe it or not i'm currently using delo gold in my 1500 (diesel oil allows you to run hotter & doesn't thin as quickly), but PSO GTX is a great oil for beetles.
Worst case scenario your oil pump might be blocked or not running properly.