Have been following the thread on Bars Leak which raised another question in my mind. When my 9000T reached about 120,000 miles and i thought on last legs(ignorance is bliss!)I started adding Molyslip at oil changes which I have always kept to every 6,000 miles when previously had only used straight oil. It is still running now(though retired)at 174,000 miles. I had always used Wynns in my Volvos but am currently again using straight oil in my NG 900T. Is there any consensus regarding the use(or not) of additives in engines?