IS - 2nd Gen (2006-2013) Discussion about the 2006+ model IS models

DOT3 or DOT4 brake fluid?

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Old 08-03-09, 12:16 PM
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Coconut
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Default DOT3 or DOT4 brake fluid?

I'm about to swap out my front and rear IS250 brakes to IS350. Should I use DOT3 or DOT4 brakefluid? Toyota recommends DOT3. What brand should I get if I go DOT4?
Old 08-03-09, 01:15 PM
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kickin8
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From StopTech website

http://www.stoptech.com/tech_info/wp...fluid_1a.shtml

Does this make DOT 4 fluids better than DOT 3 fluids? Not always. Remember, the boiling points listed are minimums and there are DOT 3 fluids out there with higher boiling points than some DOT 4 fluids. The real differentiating factor should be that if you run a DOT 4 fluid you really should change the fluid more often than if you use a DOT 3, if for no other reason than the rapid fall off in boiling point with time.
Old 08-03-09, 01:56 PM
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Coconut
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thanks for think! great reading.

"As a trailing note on the DOT ratings, if your car was designed for a particular type of fluid (especially prior to the development of DOT 4 fluids), you should make every attempt to stick with that fluid! For example, if your car was delivered with DOT 3 fluid, the internal components of the system (seals, brake hoses, and fittings for example) were specifically designed and tested for compatibility with DOT 3. Because DOT 4 fluids contain a different chemical composition, the system may not necessarily react in a positive fashion to the borate esters floating around in the mix."

So I guess should just stick with the OEM TOYOTA DOT3.
Old 08-03-09, 04:25 PM
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Originally Posted by Coconut
thanks for think! great reading.

"As a trailing note on the DOT ratings, if your car was designed for a particular type of fluid (especially prior to the development of DOT 4 fluids), you should make every attempt to stick with that fluid! For example, if your car was delivered with DOT 3 fluid, the internal components of the system (seals, brake hoses, and fittings for example) were specifically designed and tested for compatibility with DOT 3. Because DOT 4 fluids contain a different chemical composition, the system may not necessarily react in a positive fashion to the borate esters floating around in the mix."

So I guess should just stick with the OEM TOYOTA DOT3.
+1
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