Q Having become frustrated by the apathy of the main Mercedes-Benz dealer close to me, I have decided to service my Mercedes C200 CDi estate myself. My question is what are the recommended fluids for the brakes, gearbox (722.6), power steering and differential? I have spoken with my dealer and he will sell me gear oil ATF+4 and differential oil 75/85 from bulk if I provide cans, etc, but will not tell me the MB part numbers or specifications. The engine oil is specified as MB229.51 (I use Castrol with this spec) and the cap on the brake fluid reservoir says it’s DOT 4. Colin Archibald
A The Mercedes part number for the gearbox is MB 236.10 (ATF) A 001 989 21 03, there are also two approved Shell products, Shell ATF 3403 M-115 and Shell Spirax ATF 3403. The product recommended by Comma oils is AQ1341L, which is possibly more readily available.
The brake fluid is actually DOT 4 Plus (part number A 000 989 08 07) which has a higher wet boiling point. The Comma product that is recommended is BF51L and is a DOT 5.1 synthetic brake fluid. This contains no silicones and can be mixed with earlier DOT 3 and DOT 4 products.
The hydraulic fluid for the steering is A 001 989 24 03 or Pentosin CHF S Hydraulic Fluid. Again, the Comma product is probably more readily available and is part number MVATF1L.
The oil in the rear axle is a MB 235.7 85w90 – unless your vehicle has a diff lock system, in which case you should use a 75w85. This recommended product is a fuel efficiency hypoid oil and there is no Comma alternative. One oil that does come up to specification is Fuchs Titan Sintpoid FE SAE 75w85 or 85w90 fully-synthetic gear oil.
The engine oil is, as you say, MB 229.51 and the Castrol product you are using is the perfect choice.