Now I'm getting worried as I've got 65,000kms on my FG and have been using Nulon 10/40 for the last 30,000 kms. I've been changing mine at 5,000 intervals and just did a change on the weekend and noticed that the colour of the oil is getting darker not quite black. After reading this I'm having second thoughts and maybe switching back to the Ford LPG oil after a oil flush.