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MG Midget and Sprite Technical - Silicone Brake Fluid Change

I am looking to (perhaps) change my hydraulic fluids over from mineral base Castrol GT/LMA to silicone (DOT4). Several bits in the archives on making this change, but wondered how many have recently done this and are they happy with the results? Any recommendations?

Regards,

Larry C.
Larry C '69 Midget

Larry,
it was discussed recently, now dropped off the bottom of the page so do an Archive search for the phrase 'Silicone brake fluid' and it's the second subject down with the same title
Nigel Atkins

Nigel,

Thanks, I found it right in front of me. Sometimes I search too quickly, and overlook the obvious!

My problem (in my old age) is getting under the car these days to service myself, and thought the change to silicone might allow longer intervals between renewing. After reading Growler's comments in the archives I think I'll stay with mineral base for now, and probably have my local shop renew with Castrol GT/LMA next winter.

Regards,

Larry C.
Larry C '69 Midget

the thought of not using a paint stripper, I have already a couple of runs on my car (don't ask) and not having to change it every couple of years is very appealing to me

my mate's just put silicone in his hardly used classic as he's overhauling the car and I must admit if my car didn't already have the cheap nasty paint stripper stuff in I would consider silicone

I'd consider using 5.1 next time if it's not silly prices and can mix with 4
Nigel Atkins

Its hard to beat castrol LMA... thats all I use....in my old toyota pick up truck... I used castrol lma in it back in 1999... 300,000 miles later, the hydrolics still work as they did in 1999, just keep topping it as the pads wear out

Prop
Prop and the Blackhole Midget

Larry: do you mean Dot4? Isn't that glycol based? Having recently been looking at brake servos I see they say not suited to silicone.
G Williams (Graeme)

Graeme
I have had Silicon in my daily driver Ford XR3i in excess of fifteen years. The car is fitted with a Servo. I have not experienced any problems.
All of my cars are long time Silicon (automec) brake fluid users.
Alan
Alan Anstead

Graeme,

You are correct, in my (feeble) mind I was thinking of silicone as a synthetic, making all else mineral. The proper term for Castrol LMA would be glycol based.

Part of my original concern was proper flushing of any glycol based fluid before using any synthetic fluid (ie, de-natured alcohol). Would I need to disassemble master, wheel, and slave cylinders to clean seals, etc. The point is now moot, as I'm going to continue with (paint stripper) Castrol LMA. NO (next owner) will need to deal with the question should they wish to.

Regards, and thanks to all for your help.

Larry C.
Larry C '69 Midget

Alan: I was pondering this question only recently while sitting in a local pub carpark! The servo information definitely says avoid silicone. What the implications may be if this is ignored I can only surmise. Obviously not instantaneous by the sound of it!
G Williams (Graeme)

I don't know for sure but my guess regarding the advice of not using silicone with servos is just because it is more compressable than DOT4 so may not allow the servo to operate at peak performance.
Bob T

This thread was discussed between 09/07/2013 and 12/07/2013

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