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I have an 88 and need to know what fluid DOT 3, 4 or 5 goes in the clutch line master cyl.

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I use Motul RBF600 and can confirm after a day at the track yesterday running a total of 2 hours at the limits of driver and machine that it held up well to the extremes in temperature. Mine is an '02 V8. Others' mileage may be different.



I have an 88 and need to know what fluid DOT 3, 4 or 5 goes in the clutch line master cyl.

Thanks
 

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I use Motul RBF600 and can confirm after a day at the track yesterday running a total of 2 hours at the limits of driver and machine that it held up well to the extremes in temperature. Mine is an '02 V8. Others' mileage may be different.
BTW -- on my V8 the clutch and brake reservoir are one and the same. Not sure if that's the case for earlier cars. In any case the Motul was great for my brakes.

Knut
 

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Not only should it be DOT 4, you should be using Castrol GTLMA DOT 4 and you should be using it in your brakes too and flushing it out and replacing it EVERY year. Just about all shops that work on British cars recommend this stuff. Seems to be the most compatible with the rubber compounds used in the brake and clutch systems. FYI, DOT 3 has a lower boiling point than DOT 4. DOT 5 does have a higher boiling point but you can never get all of the air out of it so it is compressible. Not good for a hydraulic system where the fluid is supposed to be non-compressable. Unless you have enough pedal travel you might not be able to stop or release the clutch. What is also good about Castrol is it is not expensive and you can get it almost anywhere.
David Teitelbaum
 

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The Motul is good stuff, but oneof the best bang for the buck brake fluids is Ford HeavyDuty - has a high boiling point and is not as hydroscopic as the Motul. The funny thing is that Ford developed it for the little old ladies who drove their Lincolns around with one foot on the brake at all times. These little old ladies knew how to heat up a braking system....hence the need to develop a high boiling point fluid.

If you are looking for some serious, serious brake fluid, go for Castrol SRF! It's been the pinnacle of brake fluid for almost 20 years. It does need to be changed more often than other fluids though, but racers swear by SRF!

 

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Regards the Ford Heavy Duty:

It seems that a few years ago they changed the formulation. Now it has the same boiling point as regular DOT 3. Check before you buy!

++++

Speaking of changed formulations, the Castrol LMA (Low Moisture Absorption) has a new package as well.



It's "Synthetic"?


:shrug:
 

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Not only should it be DOT 4, you should be using Castrol GTLMA DOT 4 and you should be using it in your brakes too and flushing it out and replacing it EVERY year. Just about all shops that work on British cars recommend this stuff. Seems to be the most compatible with the rubber compounds used in the brake and clutch systems. FYI, DOT 3 has a lower boiling point than DOT 4. DOT 5 does have a higher boiling point but you can never get all of the air out of it so it is compressible. Not good for a hydraulic system where the fluid is supposed to be non-compressable. Unless you have enough pedal travel you might not be able to stop or release the clutch. What is also good about Castrol is it is not expensive and you can get it almost anywhere.
David Teitelbaum
+1,000,000. Castrol LMA, changed yearly, nothing else. EOM. :D
 

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Re: Expensive DOT4 fluid for use in clutch:

If the clutch and braking reservoirs are separate that is overkill for a clutch system. It does not see nearly the same heat as brakes. Brake fluid heats up because heat from the pads is transferred through the backing plate through the piston and into the brake fluid. Clutch hydraulics do not heat up like that and therefore never see temps where the fluid begins to boil. I have yet to ever drive a car where the clutch gets soft due to fluid boiling.

HOWEVER if you are talking about a car that shares the same fluid for the clutch and brakes (such as the Elise/Exige or apparently the newer Esprits) then of course you will want to change with a quality high-temp DOT4 fluid.
 

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The Motul is good stuff, but oneof the best bang for the buck brake fluids is Ford HeavyDuty - has a high boiling point and is not as hydroscopic as the Motul. The funny thing is that Ford developed it for the little old ladies who drove their Lincolns around with one foot on the brake at all times. [/img]
Nonsense. It was developed for heavy-duty trucks.
 

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Nonsense. It was developed for heavy-duty trucks.
just telling you how the legend came about.

I don't really care why they developed it, but it is the best "on the local shelf" stuff you can get. Ordering specialty fluid, you can find better, though.
 

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Re: Expensive DOT4 fluid for use in clutch:

If the clutch and braking reservoirs are separate that is overkill for a clutch system. It does not see nearly the same heat as brakes. ... I have yet to ever drive a car where the clutch gets soft due to fluid boiling.

Not boiling, but excessively compressible.

Do a Google Search for "Red Hose Syndrome" and you will get lots of bandwidth about Esprit clutch systems not working well on the first warm day of the season...


Replacing the brake fluid every year, and the clutch fluid every other year, is cheap insurance. :up:
 

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Red Hose Syndrome, aka soft hose syndrome, is not unique to Lotus. It's cousin, Delorean, also suffers from the same malady. In both cases the fix is to replace the clutch hose with a steel braided replacement. You don't lose any pedal travel inflating the hose anymore. Happens because the plastic hose softens in heat and since it is comparatively long a small amount of flex over it's entire length results in a large loss of motion at the slave cylinder. They, along with all British cars, do not like old brake fluid. It rots the internal bores of the cylinders and when the seals pass over the corrosion it tears them up and they start leaking. The best way to prevent that is to flush the fluid annually. Brake fluid absorbs moisture from the air and it makes it corrosive. The metal used for the cylinders seems to rot easily in the presence of contaminated brake fluid. American cars seem to be invulnerable to this. I have had American cars for years and NEVER changed the brake fluid. In some it looked like mud but still worked and didn't leak! I guess nowadays with ABS all cars are more sensitive to old brake fluid though. Braided steel brake hoses will also stiffen the brake pedal.
David Teitelbaum
 
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