I made a mistake reporting the fluid-oil my friend had used in the gearbox of his '60 BN7 who experienced a gearbox failure requiring replacement.? He had been using Redline 75W90NS whether that is the MT or MTL fluid-oil. I use?SAE 30 non-detergent oil in my '60 3000 gearbox and its overdrive and will probably not ever use anything else, period.