Hi guys, it has probably been asked before but I would like to know if I should be using a "thicker" oil for my F6 since it has clocked up nearly 115000km.I am currently using Nulon 10w-40w synthetic and have been since 60000km and not had a drama,and I change it every 7500km.Also another question is what psi should my oil pressure guage be reading when the engine has reached operating temperature eg: 20psi?? 30psi I would appreciate your replies. Ed.