Noob Brake Fluid Question

[napower]

hey sirs and sirettes,

dumb question i think but i got sold dot 4 brake fluid and my cap says dot 3 only. is dot 4 better and or acceptable even though its says dot 3 only?

shank you

[zebra]

dot 3 is the minimum required

[Samuel Leonard]

Dot is an abbreviation (can't remember it) but it's basically a national standard. Dot 3 is a lower boiling point than dot 4 and 4 is lower than 5. 5 is expensive and needs to be replaced frequently.

Like the other guy said, dot 3 is the minimum you should put in. Go for dot 4 and you'll be good for 2 years at least.

[Kinks]

DOT 3, DOT4 and DOT 5.1 are all compatible, with the higher number having a higher boiling point.

DOT5 is a silicon based brake fluid and does NOT absorb water, if you don't change it VERY frequently the water pools in your caliper and when it boils your brakes will fade very easily. The other fluids absorb water and don't reduce their boiling point as much so they are suitable for road cars with normal service schedules. DOT5 is for race cars only where the brakes are constantly serviced.

[bazz84]

sorry to bring back and old thread, but does anyone use castrol super DOT4 on their r32 GTR? its glycol based so i thought it would work, but the bottle says not to be used when dot 3 only recommended

[Moodles2]

I used regular castrol DOT4 for my clutch. Are you sure it doesn't say "not to be mixed with dot3" or something like that?

Other than boiling point different, DOT3 is chemically the same as DOT4 except DOT4 contains borate esters. DOT4 might theoretically eat away at the rubber seals or the rubber brake lines if it's a "DOT3 only" system.

Knowing Nissan they were most likely looking ahead, and made the system compatible with DOT4, it's just the DOT 4 standard hadn't been formally introduced yet (no idea what year it was introduced).