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TR4/4A Brake / Clutch Fluid for TR-4A


Senior Member
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I've always used Castrol GTLMA fluid for the brake and clutch system on our TR 4A. The Brake access cover says to use only Castrol Fluid. Castrol seem to be no longer available. What is the current recommendation?



Senior Member
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Castrol was vegetable based, not pertrol based. Hence castor oil. My advice is DOT 5 after purge. Cannot know how "rubber" parts may react. They may have changed to an oil base to be like others. Hope this is some help.



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I had the same problem in a car where I did not use silicone, but I am not sure what I did to fix it. I believe I was told LMA is the substitute and to use it because like you said plain Castrol is not around. I think LMA bottle even says synthetic I learned a lot from suppliers/parts places that sell only brake and clutch parts. Around here we have a couple plus they usually have a large selection of brake fluid types. The forum guys are smart but some of those general auto parts places are scary and terrifying.

Geo Hahn

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...I think LMA bottle even says synthetic...

As I recall Castrol won a legal battle that allows them (and anyone) to label a brake fluid (and other products) 'synthetic' since synthesis simply means 'the production of chemical compounds by reaction from simpler materials'.

Yeah, they sort of did for 'synthetic' what trailer parks did for the word 'estates'.

I only use DOT5 but that is a choice & opinion not universally shared.


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I'm using Silicone DOT 5 in my Healey with 4-wheel discs. It's great for paint and cleanup, but I've always had a somewhat spongy pedal. Silicone captures air in the fluid which can be in there for ever.

When I converted, I cleaned the cylinders and blew out the lines with brake parts cleaner and compressed air. Replaced all the rubber parts in the calipers and masters as well as clutch system. It's not that expensive for the rebuild parts and I wanted to avoid any compatibility issues.

FWIW commonly available DOT 3 and 4 fluids have been OK in our systems for decades. I previously used NAPA DOT 4 because it came in quarts.


Obi Wan
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I’ve changed over to dot 5 as well and can’t tell any difference in pedal feel. Even if the pedal was a little less solid than before I think it’s a good swap considering the advantages.


Obi Wan
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Castrol is readily available, AutoZone, O'Reilly's and online. I always keep 2 qts on shelf. Prestone makes a DOT 4.


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Yeah, Castrol brake fluid is still around,,,but it lost the LMA on the label and added the word "synthetic", which I believe it always was. Was there ever a 'natural' brake fluid ?
The engine oil was and may still be available as castor bean oil and it smelled wonderful in two cycle engines.
I finally broke down and switched to DOT5 silicone, just a few years ago..I couldn't tell any difference in the pedal.


Jedi Knight
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When I lived in Sacramento I used a brake shop on 16 th street for my cars and such I do not remember name of shop just a hole in the wall place but knew a lot. They could be worth a call. Madflyer
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