hey guys, my brake pedal has been feeling spongy lately, is it ok to use dot4 oil instead of dot3?

let me know

thanks

Konstantin

 

Bleed the brake with dot3 or dot4 and they will feel alot better. Go to this thread, there is some good info:

http://forums.maxima.org/showthread.php?threadid=46854

 

Nissan recommends DOT3 but DOT4 is acceptable. A spongy brake pedal is a sign of air in the hydraulic lines. Bleeding them should resolve the problem.

 

I understand that, the reason I asked is because I see some people putting dot4 in their cars, I'm just curious if I should also put the dot4 in my car, will it worsten the braking? because if the dot4 has a higher boiling point then dot3, wouldn't it be better to use dot4?

I don't know too much about this, that's why I'm asking, not trying to be a pain in the a$$

thanks for help ahead of time Daniel

 

A high boiling point is important for a real on-the-track racer, or a driver who lives in a mountainous area and uses his brakes a lot. Those people might prefer DOT4.

DOT3 and DOT4 brake fluids are glycol-based. They are hygroscopic which means they have an affinity for water. Water contamination is the principal reason for degradation of brake fluid. DOT4 fluid is more hygroscopic than DOT3. Therefore the person who drives in an ordinary circumstances may prefer DOT3 to DOT4. Nissan does not include replacement of brake fluid in any scheduled maintenance. Perhaps that is the reason they specify DOT3 rather than DOT4.

 

thank you, this makes more sense
is there fluid which isn't hygroscopic?
if there is, whould it be used?

 

DOT5 brake fluid, identifiable by its purple color, is a silicone-based product, with a higher boiling point, (260C or 500F) and no affinity for moisture. DOT5 fluids are more expensive than the glycol brake fluids. Due to their air retention properties, DOT5 fluids make bleeding air from the brake system more difficult than DOT3 or DOT4 fluids.

DOT3 and DOT4 brake fluids are inexpensive and readily available. Clear to amber in color, they are glycol based fluids. These fluids cause rubber parts of the hydraulic brake system to swell slightly, improving sealing and preventing leaks.

 

I'd like to add several points about DOT5.

1. It is NOT compatable with DOT3 or 4. You MUST drain and flush all of the DOT3/4 before you use it.

2. DOT3 is pretty hard on paint, DOT4 is VERY, VERY hard on paint, DOT5 will not harm paint.

3. Last time I checked (5 years ago) DOT5 was 4 times the cost of DOT4.

4. DOT5 destroys old, natural rubber seals. I switched to DOT5 in my '76 MGB and two weeks later I had to rebuild the master cylinder and the wheel cylinders. The old Geurling (sp?) seals turned to mush.

 

thank you, this information is very usefull, I think I'll just use the old dot3, or maybe dot4, depends if I want to torture myself

 

just to add: DOT 5 is not compatible with ABS-equipped vehicles.