, hey everyone, i need to change my brake fluid, and i was wondering if dot 5 (silicone) would be ok, i can get it for the same price of dot 4, im currently using synthetic in both the engine and tranny, so i just want the best fluids possible. just wondering if this were possible, and teh pros and cons


erik, in N.S. Canada

when i was having a debate with someone else concerning this? i insisted that dot5 was a big no no, but he insisted equally as much that dot5 is perfectly fine and in fact better, even in our vehicles. he backed it up by saying he was a former military person in charge of maintaining tanks and other military equipment, and they all used dot5.

i was looking for some backup then. oh well.

:-)

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Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

Did he say that 740s should use treads instead of tires too?
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Paul NW Indiana '89 740 Turbo 108,000

Silicone fluid is forbidden in your brake system: it will destroy all the seals. It also forces water migration to low points and will encourage corrosion in the calipers.

I think this "absolutely not" happened to me. LHM fluid (it's used in those wierd Citroens) was inadvertantly added to my 740 diesel by a roadside rescue mechanic when my clutch slave cylinder failed. A new clutch slave cylinder was subsequently fitted by a friend who unwittingly used the same fluid. This resulted in a second clutch cylinder failure (yes the seals swelled).

Subsequently we have replaced brake slave and master cylinders, replaced clutch slave cylinder seals, and again replaced clutch slave cylinder (this time with a secondhand unit). We have experienced problems with bleeding.

Finally another mechanic has looked at the car. He has managed to bleed the brakes OK, but the clutch would not bled. He has now done it by filling backwards, with tha aid of a pump, from the slave cylinder, like he has had to do with some trucks/lorries.

Is this the way to do it, or is there still something wrong elsewhere (seals we have missed perhaps!)?

Thank you.

Terry Turner.

Ate (who makes your rear brakes) makes Ate Super Blue Racing fliud (DOT 4). Besides being an excellent fluid, its color showing up at the bleeders signifies a complete flush (no excess & wasted fluid).

It costs more than Castrol LMA — $7.95/Liter at FCP Groton, but I've found that one liter is more than enough for a complete flush, based on color evidence at the bleeders.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

Actually... super blue is not DOT 4 approved (AFAIK due to the coloration).

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alex

'89 765T, 170k miles.

Actually...it is, according to the statement on the can:

"This DOT 4 motor vehicle brake fluid
conforms to the US safety standard FMVSS
& 571.116/DOT 4/DOT3, SAE specification
J 1703 (supercedes 70 R1 and 70 R3) and
ISO 4925"

Close enough for me.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

Ate also has a DOT4 yellow fluid. Some people like to alternate colors between changes.

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Paul NW Indiana '89 740 Turbo 108,000

the silicone requires changing all the rubber in the system to avoid contamination. silicone is also spongier under pressure, the pedal feel is alot softer. stick with dot4, castrol lma is better. good luck, chuck.

NO! From what I've read, both about Volvos, and about RX-7s, NO, NO, NO. The DOT 5 fluids are silicone based and are incompatible with the seals or materials in systems that are not designed for them.

Have read that there are DOT 5+ (I think) fluids that should be compatible with older systems, but I won't take that chance on either my new Turbo 745 or my RX-7 (nor in the Tercel). I use Castrol GT LMA (low moisture activity), a DOT 4 fluid. Works fine, and the low moisture activity is a big plus here in Florida.

Just be sure to change it every year if you live in a soggy, humid, dank swamp-like place like Florida (really love it, it is my home, but gotta be honest), or every two years if elsewhere.

Scott Cook
1991 745T, 1985 RX-7 GSL-SE, 1986 Toyota Tercel (Don't laugh, it is reliable and faithful, AND gets 41 mpg!)