The rear differential is an often neglected but essential component of the high performance drivetrain in an Aston Martin DB9.  Most people know about engine oil and transmission fluid, but what about the unsung hero of the rear wheel drive – the differential? All Gaydon era Aston Martins (DB9, Vantage, DBS, Rapide and Vanquish) have a ‘limited slip’ high performance rear differential.   It is lubricated by special gear oil (differential fluid).  For cars with automatic transmissions Aston Martin recommends it be changed every two years as part of the 2 year annual service regime (learn about that here).   I dug in and researched what the correct differential fluid.  It is different for manual or automatic transmission vehicles, so read on which one is right for your car. Continue reading “Differential Fluid for an Aston Martin DB9” →