Joe '87 S4

My brake fluid light came on today. It's just over the min level. What fluid should I use to add a little? I bought some Prestone DOT 3. It complies with the Safety Standard 116, and meets SAE spec J1703. After I got home I realized it's synthetic and thought I remember reading NOT to use synthetic?

Bertrand Daoust

I put some Prestone Dot 4 synthetic when I flushed mine.
Why can't we put synthetic and where did you read that?

Mrmerlin

I would suggest to buy a can of ATE super blue racing fluid flush the system out
using the syn fluids can cause the seals to swell and thus cause the brakes to lose performance.

you usually wont see a sticking brake system from a fluid swap till about 6 weeks after the change.

ATE is the MFG of the brake system

blown 87

I would also use the ATE fluid, or a good DOT 4 non synthetic one.

pjg

I thought it was silicone brake fluid that we should avoid, and synthetic Dot 4 was OK.

JHowell37

I would check the thickness of your pads and have a brief look over everything to make sure you're not leaking or in need of a pad replacement.

Joe '87 S4

Thanks for the replies.
Betrand, I'm not sure where I read it or if I if maybe heard it at one point. That's why I was checking.
Paul - The manual says not to use silicone.

Captain_Slow

I alternate between ATE Super Blue and their one-notch-lower (but almost the same) amber. This way it's easy to see when one or the other is flushed out completely.

martyp

Is the amber ATE 200 really one notch lower or just a different color?

AO

Don't know, but it for sure doesn't have "Super" in the name, so how good can it really be?

That's what I use BTW, alternate between super blue and the ATE 200. Flush every 2 years.

123quattro

You can mix and match dot3, dot4, and dot5.1. They are all polyethylene glycol-based. Dot5 is silicon based and not compatible with the others.

SteveG

So there is dot5[.0] and dot5.1?

Bilal928S4

I have used this for a while with no ill effects on the 928 and BMW's.
http://www.valvoline.com/products/br...brake-fluid/28
Bilal

GlenL

Unless you are actually tracking the car, "hard" street driving doesn't count, you can use common DOT 3 in the system. Get a pint for topping off and a quart for flushing from any auto parts store.

Check for drips and wet spots on the calipers. If the warning comes on again in the next year than you should look harder for the leak.

Captain_Slow

Yes, I do think it's just a marketing difference... they are essentially the same if not exactly the same.

"Is the amber ATE 200 really one notch lower or just a different color?"