Mercedes servicing explained: Service A, Service B and ASSYST

Mercedes puts it simply: A is the minor service and B is the major one. Which you get depends on the age and mileage of the car, and they alternate, so a car in regular use works through A, then B, then A again.

Service A is the lighter visit, built around fresh oil and a filter with a check over the car. Service B is the fuller one, adding more of the consumable parts and a longer list of checks. That alternation is why the bill isn't the same every year, and why a quote that sounds high may simply be a B.

If you'd rather have the exact list for your car than a general one, Mercedes publishes an Electronic Service Sheet: you enter the model and the registration date and it tells you precisely what that service should include. That's worth doing before you book anything, with anyone, because it turns a vague quote into a checkable one.

ASSYST, and ASSYST PLUS on newer cars, is the service indicator. Rather than counting down a fixed mileage, it works out when the car is next due and tells you the date, flagging it roughly a month ahead so you have time to arrange something.

That month of notice is the useful bit. A Mercedes rarely surprises you with a service. It warns you, and that's a scheduling prompt rather than a problem. What it doesn't tell you in plain words is whether the next one is an A or a B, which is the part that changes the cost, so it's worth asking when you get a quote.

Like most German manufacturers, Mercedes approves specific oils rather than accepting any oil of the right grade, and the approvals are published as numbered sheets. Which one your engine needs depends on the engine and on what is in its exhaust system.

The practical point is the same as on any modern car with a particulate filter, which includes every current diesel and a lot of recent petrols: those need a low ash oil, because ordinary oil leaves deposits that block the filter over time. Fitting a cheaper oil that does not carry the right Mercedes approval is a saving that shows up later as a much larger bill, and by then nobody connects the two.

We check the requirement against your car rather than assuming it. If you have bought oil yourself and it carries the correct Mercedes approval, that's fine and we'll use it.

Most modern Mercedes diesels use AdBlue, a urea solution injected into the exhaust to cut nitrogen oxides. It's a consumable, it runs out, and the car will warn you well in advance with a countdown of remaining miles.

Take those warnings seriously, because the consequence is unusual: once the countdown reaches zero the car won't restart. Not a limp mode, not a warning light you can live with for a fortnight, it simply won't start. Topping it up before that point is straightforward and cheap. Being recovered because you'd ignored a countdown isn't.

The same thing that catches BMW owners out applies here. On most modern Mercedes the parking brake is electronic rather than a cable, so the rear caliper pistons are driven by motors and cannot be wound back by hand to make room for new pads. The car has to be put into a service mode to retract them and reset afterwards.

It's a question of equipment rather than difficulty, and it's worth asking about before booking rear brakes with anyone. Front pads on a Mercedes are a straightforward job at your home. Rears need the parking brake handled properly, and forcing it damages the caliper.

Servicing, oil and filters, brakes, batteries, diagnostics and the everyday electrical work are all done at your home or work, on a Mercedes the same as anything else. What we don't take on, on any make, is work that genuinely needs a ramp and a workshop: major engine and gearbox rebuilds, automatic gearboxes and cambelts among them.

We work on all makes and models, so the German cars are where James is putting his focus, not the limit of what he does.