Do not for a moment trust the majority of brake fluid testers.
The ones that work boil the fluid and check the temperature that it boils at and these are near £800 to £1,000.
The testers most garages have are a visual unit or an electric unit that tries to check water content via butting a current via the fluid.
There are no proven results from the cheaper units and very few garages can afford to purchase the very expensive units therefore I would change the fluid at the advised intervals.
As always there are people on this forum and other motoring talking shops that are proud as punch in saving the cost of changing brake fluid, not changing crush washers on drain plugs and not changing antifreeze and boast of driving on tyres over 10 years old.
To them a penny saved is a prisoner indeed.
