Super dot4 brake fluid and dot3 mixable?

[lh59]

I'm going to the garage this Monday to get my brake fluid flushed with four bottles of Super dot4. However, the brake fluid reservoir on my Yaris indicate dot3 only. The reason I'm using the super dot4 is because I pick up the new sealed bottles from my friend who is moving to another state.

What do you guys think about the super dot4 on the Yaris? Will dot3 last longer due to less additives being added? I am just doing normal everyday driving.

[Lux]

All types of brake fluid have a service life of 2 years.
Unless the system professionally bled completely with new fluid, the fluid's boiling point will always be the lowest grade (and condition) of fluid present in the system.
Should use the factory specification for brake fluid for best compatibility. The reason for it lies in the hoses and seals, which, in some cars, may react negatively to the different chemical composition.
Due to the nature of your driving, there will be no benefit in using DOT4.

[Geoff Peace]

Originally Posted by lh59

I'm going to the garage this Monday to get my brake fluid flushed with four bottles of Super dot4. However, the brake fluid reservoir on my Yaris indicate dot3 only. The reason I'm using the super dot4 is because I pick up the new sealed bottles from my friend who is moving to another state.

What do you guys think about the super dot4 on the Yaris? Will dot3 last longer due to less additives being added? I am just doing normal everyday driving.

The only difference between DOT 3 and 4 is the boiling point. DOT is slightly higher. There is lot of nonsense peddled about renewing brake fluid every two years. It represents a good profit for garages. The cricial factor is the moisture content, which can be measured. Garages do not do this because there is no profit. The question I ask is why was it never a stipulation on cars such as the E type Jaguar and Aston Martin in the sixties and seventies? Answer, nobody had yet thought of this way to make a quick buck by mentioning the word safety! It justifies any rip-off these days.

Regards Geoff Peace.

[lh59]

From what I've read from the web, it seems that Toyota insist on the dot3 due to lower viscosity. This is getting a bit confusing. I'm only considering using the 5 bottles of super dot4 because my mate is giving it to me for free

[ciscobear]

Yes you can use the DOT4 in your DOT3 system. Not a problem, did it on my Levin using Castrol GT LMA. DOT5 however is not the same.

[bronsin]

DOT 3 and DOT4 are required to be compatable with each other so I see no problem. If it was me I would remove a much fluid from the resavoir as possible before adding the DOT 4. Then bleed most of it out at each bleeder one at a time and refill so basically you replace all the stuff in there with DOT 4.