Norries right - this engine has a cam chain rather than a belt and needs no attention. The time intervals for changing other items assume average mileage is being done, for example spark plugs 5 yrs/100K miles. But its a good move to change filters/plugs more regularly if you have the bits to hand and you have the time to do it yourself. However, re brake fluid - to change this every 2 years on a car that is only doing low miles is waste of time and money. DOT 4 brake fluid has been around for many years and is used universally. Its only in recent years that this fad of a 2 year change was brought in - previously the fluid would never be changed and would stay in the car all its life. Brake fluid does not deteriorate over time and historically was only changed were it was used in very high temperature applications ie above its normal operating range in racing cars etc when it was often "boiled up" in the pipes causing a spongy pedal. There was some concern that rust particles could accumulate inside the braking system over a long time through corrosion of components and some car makers then started to recomend this. To change after 20K in a Merc is pointless, but if the customer is happy to pay the price thats good for the garage.