Having read the thread on lathe spindle lubrication and the various opinions about the damage or otherwise of the use of an unsuitable fluid here are 2 tales both serious and potentially FATAL !

The first involves 2 very different vehicles but the same end cause, incorrect fluid. An almost new JCB telehandler  that the driver had observed that the level of fluid in the reservoir had dropped a little – the local rep topped it up with DOT3/4 brake fluid ! A little while later the brakes started to stick and play up, I was called in ! The cap of the reservoir clearly stated the use of a MINERAL OIL was needed NOT a Glycol based fluid ! The local agents had to pay to remove both axles to replace the inboard brake seals and the master cylinder as all the seals had turned almost to a soggy mess. The second was a Nissan Bluebird where the master cylinder and steering reservoirs were side by side ! Having had trouble with the brakes – the seals had gone funny and been replaced, I was travelling at high speed approaching a bend, touched the brakes and the whole lot locked up ! First I hit the bank, then several pirouettes ! When the noise and dust settled I was sitting in the middle of a COMPLETELY destroyed car, only by the grace of God was I uninjured. Investigations showed that the fluid in the system was RED – it was steering fluid !

The second was a Rangerover, careful elderly driver ! Sunday afternoon and having travelled 15 miles applied the brakes as a roundabout came up – NOTHING ! No brakes at all ! Drove home VERY carefully on the hand brake and I got a call ! Checked the brakes – THEIR FINE ! I’d heard tales but never seen it ! Drove the vehicle for about 2 miles without touching the brakes and then checked the discs on the front, N/S was warm ! After 15 miles the dragging caliper had heated the fluid and boiled the moisture it had absorbed over 10 or 12 years to produce a volume of steam which is compressible = NO BRAKES. As the system cooled down the steam condenses back to water and the brakes are fine again. In cases of mishap where the driver claims total brake failure yet on investigation nothing seems wrong, this is often the cause ! Now you know why manufacturers advise that the brake fluid is changed every 3 years ! Some military vehicles back as far as the 1960s used a silicone based fluid to avoid this issue.

Cautionary tales ?  Noel.