you are probably looking at normal reaction to moisture and other things that occur with mileage and brake fluid. brake fluid is hygroscopic, meaning, it's a magnet for water. so much so, that moisture will wick into the fittings and through the rubber of the hoses. that's why bleeders and hose junctions rust together.
volvo starting recommending changing brake fluid every 2 years about 86. it was part of the 5 yr rust-through warranty. funny thing happened when the fluid got changed in the later cars-not as many master cyl failures. when i started there in parts in 85, we stocked 10-12. when i left in 89, we were down to 5. with abs, a change is mandatory. i suspect the 850/s-v70s suffer abs module problems because of lack of changes. gm has a high abs module failure rate they have linked to poor maintenance.
on the dot3/4 debate: dot 4 has a higher boiling point. castrol uses a natural mineral oil base for the natural rubber that was used in england and europe. the u.s. dot 3 has a synthetic base and would attack natural rubber. i can't say what rubber the factories in europe are using now. lma in castrol means "low moisture affinty" whichs means it's trying harder not to be hygroscopic. just my 2 cents, chuck.
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