Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing DOT 5 Brake Fluid - Any Good?

I've only had a total fade once on an MG Metro coming down Porlock Hill in North Somerset, or is it Devon. Anyone who knows that hill knows how steep it gets, the run in is a good half a mile straight, and steep, then a 30degree left, quickly followed by probably a 120 right. The gradient never eases, and after another half mile, another 120 left, where it then starts to ease, but as you come into the village at the bottom, there's a very short section of single track betweem walls. It was on the last section that the pedal went to the floor, and there was nothing, pumping made no difference. There was nothing coming the other way through the tight spot, and we coasted into the village with the handbrake. We were lucky!

You were lucky Dave. I know that hill well. The runoffs are not brilliant. When we used to go there many years ago the road would be littered with overheating cars trying to get up it...

Sorry to disagree Deejay, agree that DOT5 has a higher boiling point and therefore used for racing but is more hygroscopic in that it absorbs moisture quicker and therefore needs changing more often. Therefore DOT4 is generally recommended for road use.

Well I ran silicone fluid from circa 1980 for many years after having an issue with boiling fluid on an Alfasud -inboard discs, Never had a problem and no sign that it could take on moisture, however you do have to totally clean your system before running silicone.

Well, maybe google is wrong??? Here's what they say, when asked if DOT5 is hygroscopic or not:

No, DOT 5 brake fluid is not hygroscopic. It is a silicone-based fluid that is hydrophobic, meaning it repels water and does not absorb moisture from the atmosphere like glycol-based DOT 3, DOT 4, and DOT 5.1 brake fluids.
Explanation:
Hygroscopic vs. Hydrophobic:
Hygroscopic fluids absorb moisture from the air, while hydrophobic fluids repel water.
DOT 5 Brake Fluid:
DOT 5 is a silicone-based fluid that is hydrophobic. This means it does not absorb water, which can be an advantage in preventing corrosion and maintaining a stable boiling point.

Only had total brake failure twice ... coming down Mam Tor towards Edale in a recently purchased and decidedly dodgy Vauxhall Victor ... remember my Mum and Sister chatting oblivious in the back as I white-knuckled it through bends thinking we were all going to die! 🙂 ... previous owner had used motor oil in the braking system and every seal was mush.

Second time was coming down off the Atlas Mountains in Morroco in the summer in a Citroen Dyane ... seemed like 100 miles of steep downhill in pizza-oven temperatures ... was glad that the outside of a big bend at the bottom was a smooth run-off into miles of desert! ... by the tyre tracks I was far from the first to be grateful for a mile or two of sandy run-off 😀

That's the only (and very extremely provoked) time I've had boiling brake fluid in millions of miles of driving (but then I've owned multiple land-rovers that have been faultlessly reliable so maybe guardian fairies visited my crib as an infant 🙂)

K

What an interesting observation in the nature of human behaviour this has been....(-:

I guess the faithful as ever will adopt their beliefs and stick to them regardless of alternative information being made available, but then the source of that information is open to question is it not...? Well definitely not for those who chose to believe black is white or the inverse...? (-:

Who here has done the tests required to prove to themselves that which they believe is the truth, the whole truth and nothing but the truth.... My guess is NO ONE... (-:

Believe in Google, Wiki, Chatbox or A.I.....? Given the content of this thread it seems there are more than enough options to choose from on TM alone...? (-:

Now whether a manufacturer in a country well known for litigation would print downright lies on their box containing DOT 5 on which it seems possible countless lives might depend upon daily.... I really don`t know for sure.

From the old box of Automec DOT 5 I have sitting beside me at this moment in time ( photographic evidence available if required...though that`s easy to fake too...(-:)

THE MOST ADVANCED BRAKE AND CLUTCH FLUID EVER FORMULATED.. NEVER NEEDS TO BE REPLACED.. WILL NOT DAMAGE PAINTWORK...LESS RISK OF FIRE..HIGH BOILING POINT OF 260Deg C

HELPS TO ELIMINATE CORROSION... ENVIRONMENTALLY FRIENDLY...TOTALLY NON-TOXIC...

TO USE SBF, SIMPLY DRAIN OUT THE OLD FLUID, MAKE SURE THE SEALS AND HOSES ETC ARE IN GOOD CONDITION, THEN REFILL WITH SBF.

There is a label supplied for attachment on or near the master cylinder, to advise that DOT 5 is in use in the system, however the description on the box is as follows :-

BOTH FLUIDS WILL WORK SAFELY TOGETHER..

Just looked around the box and there is a label on the bottom with a pickdate 20/11/01....This fluid was given to me a few years back by a friend, lay in my garage for a number of years, until as I mentioned earlier I decided to clean up my callipers and replace the pads, discovering torn dust seals, I replaced them, and used the now proven far from "new" brake fluid in my +8 to flush through the system... and that is still the fluid that is in my Mog today..

My Mog has sat for many years while I was involved in various self build projects, rarely used but taken out for an occasional blast to blow away the cobwebs, so not the best use of such a wonderful machine. Automec Dot 5 in use in both brake and clutch for the 23 years I have owned it..... I guess I too am a believer... Just like the Monkeys..? (-:

I am not of the type who needs to win arguments, just seeking to SHARE experiences in the hope that it might help anyone, and I have made many mistakes along the way...

As ever.. each to their own..err.. beliefs..(-:

The way I see it, Dot 5 may well be objectively better than Dot 4, but that's no reason to go putting it in our cars.

After all, if we wanted cars which were objectively better, we wouldn't be driving Morgans in the first place

I guess I would be a fool to think Morganeers might ever value ORIGINALITY over MODIFYING their Morgans in search of improved performance or reliability...? (-:.

I have always resisted the "filled for life" approach, whether this is brake fluid, coolant, gearbox oil or axle oil. "Things" wear. That;s what "Things" do.

Brake fluid comes out dark after two years. Gearbox oil and diff oil comes out dark after a couple of years, even when "they say" it is good "for life".

So my approach has always been to replace such lubricants as I feel necessary, and never regretted that, after seeing what comes out. I also accept the alternative approach to fit and forget, but that's not the way I do it.