the boiling point of brake fluid decreases over time because it absorbs moisture. new fluid may boil at 400 degrees, while the fluid in your pontiac would probably boil at 220. if you were descending down a mountain road, your pontiac fluid would boil and you'd fly off the mountain, while the benz with new fluid would be fine. fluid costs like $10 for the good stuff (ATE) and you can get a vacuum or pressure bleeder for $20-45.

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2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car