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Brake fluid questions

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vagt6

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I recently overhauled the master cylinder in my LBC (yes, I confess it's an MG - but I'm really a Triumph guy at heart, sadly with no Triumph at present) and wonder if I MUST use Castrol GT LMA brake fluid.

It appears that Randall has done a bit of research on this subject, and contributed to the Buckeye Triumphs site as well. Randall, your input here would be most appreciated.

From my research it seems the the Castrol fluid is vegetable based (?) and is not prone to eat the rubber bits in the brake hydraulics. Is this factual? Is Castrol GT LMA the only feasible way to go?

No stores in my area seem to carry the Castrol fluid, plus my car is up on jackstands waiting for more brake fluid (I ran out of the Castrol fluid while bleeding the system).

Many thanks to all for the input.
 
Me personally only use castrol brake fluid and I have had no problems. so If I were you I would stick with castrol

Hondo
 
I have a friend whose Spitfire MkIV I took care of for many, many years. As religiously as I'd add GT/LMA to its hydraulic systems when needed or when work was done, I knew he'd occasionally top things up with Prestone or other brands. Fact of the matter seems to be that, pretty much as the manuals said, any fluid that met "standards" seems to be fine. There may well have been some compatibility problems back in the 1950s and maybe early 1960s, but I've never experienced it.

That said, I've been able to find Castrol GT/LMA in Pep Boys in recent years, and I continue to use it.
 
Personally, I'm a big believer in DOT 5 silicone, which is appears to be compatible with both the old British brake seals and the modern ones. It lasts forever (no need to change it every few years), and won't damage the paint if it does leak. It also suppresses corrosion very well, while DOT 3/4 brake fluids promote it. It is more expensive and hard to find on the shelf, but IMO it is worth every bit. (And TRF carries it at a good price, so not that hard to find.)

One of the shows a few years ago (probably TRfest), there was a very pretty TR4. Nicely restored, gorgeous paint job ... except where the MC had leaked on the way to the show and now there was a big swath of damaged, peeling paint from the MC area all the way down the bulkhead. The owner was practically in tears.

The compatibility problems do seem to be a thing of the past today, but in 1978 I convinced myself that there was indeed a problem. Brand new Girling seals in all cylinders, brand new American brake fluid (Wagner DOT 3 as I recall), parked the car for just a few months, seals were ruined. Both brake & clutch were too dry to work, and the remaining fluid was dark with dissolved rubber from the seals. Even though I've not heard of anyone having similar problems since 1985 or so, I'd still find the Castrol if I weren't using DOT 5.

Unfortunately it's too late now, but if you had called TRF this morning, you probably could have had either Girling or silicone by Monday. They do offer overnight shipping (at UPS One Day rates).

DSCF0002_cropped.jpg
 
If your ever in a pinch to find Dot 5 just stop in your local harley Davidson dealer.Its the standard for all newer HD,s,and their dealerships are just about everywhere.
Tom
 
Dot 5, Valvoline Snytec, most Advance stores. It's been in my Roadster and TR6 for 6 years, and they set around a lot, with no leaks except on one wheel cylinder that was rebuilt 7 years ago. It was questionable at the time.

Wayne
 
Mark,

I agree with Randall on silicone DOT 5 brake fluid as well for all the same reasons. I originally used it because it didn't harm paint but not absorbing water is a big plus. I mentioned in another thread here that the clutch in my TR4A which I did 25 years ago with silicone brake fluid is still working (the last 18 years have been non-mobile).

Note that you can get a quart from Amazon right now for $13.89 and it's eligible for Prime 2-day shipping (if you subscribe to Prime).

Oh, and DOT 5.1 is not the same as silicone DOT 5 brake fluid.

Scott
 
Don't think Valvoline Snytec is Silicon.
 
trrdster2000 said:
Dot 5, Valvoline Snytec,
Click to expand...
'Syntec' is a Castrol name; Valvoline uses 'Synpower'. And neither one is DOT 5 silicone.

As I recall, they aren't DOT 5.1 either, although since the Valvoline Synpower brake fluid seems to have been discontinued, it really doesn't matter.
 
Just remember, if you want to put DOT-5 in, the system must be free of any DOT 3 or 4 to be sure of any incompatibility problems. If your system has 3 or 4 in it now, easiest thing to do is put 3 or 4 back, regardless of who makes it, just go by the numbers! My 1980 Ford Ranger pickup has had DOT 3-4 in it since new and it has never given me any problems, at 250,000 miles, it still has the original wheel cylinders and they don't leak. Lucky? maybe, but lack of continued maintenance is usually the reason for failures. JMHO. PJ
 
Thanks to everyone for the input. I'm going to the closest auto parts store, probably Auto Zone, and get some generic DOT 4 fluid and pour it in there.

However, next time I'm in Richmond (65 miles from here) I'm loading up on the Castrol fluid. Or who knows, maybe I'll go to DOT 5 and be done with it.

At any rate, sorry to bother you all with what may seem to be a somewhat pedestrian query. But youse guys' opinions and specific experience with these cars are important to me, and I appreciate the responses.

Cheers to all, and again, muchas gracias! :thumbsup:
 
PAUL161 said:
Just remember, if you want to put DOT-5 in, the system must be free of any DOT 3 or 4 to be sure of any incompatibility problems.
Click to expand...
Mostly a myth, IMO. DOT 5 is fully compatible with all DOT 3, 4 and 5.1. I have done several cars now by just bleeding each wheel until clear purple comes out, and it works fine for me.

For example, my 80 Chevy had a front caliper start leaking at about 80k miles. Changed the caliper, bled DOT 5 through all 4 wheels, and literally never touched the hydraulic system again until it got sold in 2005 with perhaps 250k miles.

Compatibility with a "standard" fluid at both high and low temperature is part of the DOT 5 specification.

Of course, fully rebuilding the hydraulic system before installing DOT 5 probably does increase the time before you have problems again. But the same could be said of changing the engine oil!
 
PAUL161 said:
My 1980 Ford Ranger pickup has had DOT 3-4 in it since new and it has never given me any problems, at 250,000 miles, it still has the original wheel cylinders and they don't leak. Lucky? maybe, but lack of continued maintenance is usually the reason for failures. JMHO. PJ
Click to expand...

Paul,

Good point that I only have my own observational evidence on the longevity benefits of DOT 5 which I've used with my TR4A, my wife's old Spitfire, a pair of RX-7's and the clutch system of a 626GT (250,000 miles and 10 years on that one).

Similar to your Ford Ranger, our 1996 Ford Contour has also not had any problems with its brake system after 15 years and 162,000 miles with the original parts and fluid. I've been very impressed with that especially with drum rear brakes and wheel cylinders since my experience is that those tend to fail first (I've never had a caliper seal fail). I am looking to do a pre-emptive rebuild on at least the rear wheel cylinders, hoses and possible the master cylinder on that vehicle this summer since I'd prefer to have the brakes not fail on my wife and 16-year son.

You mentioned lack of maintenance as a cause for failures, but the only maintenance I could come up with that would possibly affect the hydraulics would be changing the brake fluid which some manufacturers include in the maintenance schedule due to the water-absorbtion characteristics of normal brake fluid. Note that the 1996 Ford Contour does not list that as a maintenance item though and I'll be the first to admit that I've never drained and replaced the brake fluid in any of our cars unless doing hydraulic work.

Scott
 
Mark, there is one other issue to bring up since you said this is not for a Triumph. If this is for a BMC car with the hydraulic pressure brake switch, it is fairly well documented that DOT-5 can quite quickly result in failure of the brake switch. There are some hydraulic switches that are supposedly compatible with DOT-5 but they cost more and I have heard of people saying that even those fail. The common work around is to adapt the pedal box assembly to use a pedal actuated mechanical brake switch and wire it in parallel to the original hydraulic switch.
 
I have a Motive pressure bleeder which allows me to flush out all of the old fluid as I push in new fluid. It's a good practice to do this every 3 years or so and it VERY easy with this setup.

btw - the HVDA hydraulic t/o recommends Dot 3/4 so I can't use silicone in the 3A with the shared reservoir. I use Castrol GT LMA (LowMoistureAbsorbtion) which comes in quart cans and is available for cheap.
 
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