[Zann]

Coming to work this morning a warning tone kept sounding as well as a flashing brake light. It would quit until I took a turn so I figured it was the fluid. I pulled over and the fluid is right at the MIN position if not a hair below it.

I guess I should add some fluid but when I stopped by the parts store they had DOT 3, DOT 4, normal, synthetic. Which to get? I'm pretty sure the fluid has never been changed so it would be whatever was in there to begin with and didn't know if mismatching was a no no.

 

[janitz]

DOT4 is spec. DOT3 would work, but is below spec.

DO NOT MIX with DOT5.

 

[Zann]

DOT4 is spec. DOT3 would work, but is below spec.

DO NOT MIX with DOT5.

Got it, so it would have DOT4 in it now so I will get DOT4. Normal or synthetic matter? What did VW put in it; synthetic or normal?

 

[janitz]

Got it, so it would have DOT4 in it now so I will get DOT4. Normal or synthetic matter? What did VW put in it; synthetic or normal?

I'm not aware of a synthetic or normal version of DOT4, I was under the impression that the DOT4 standard specified materials etc, so it would only be one type with a polyethelyne-glycol base. I guess maybe the source of it could be synthetic, but the actual product is likely no different.

DOT5 is silicon based, so they don't mix.

 

[Zann]

Thanks for the quick answers!

 

[janitz]

I took a look at ID Parts where I get most of my diesel bits and pieces, and they have a recommendation to order the VW OEM fluid over the "performance" brands they carry.

I think if you do need to add fluid that you should check your brake lines to see if they're cracked or worn and causing a leak. It's a pressurized sealed system so you shouldn't really see the fluid level drop. If it does drop then fluid is leaving the system, if fluid is leaving the system then you've got no pressure, and no brakes.

About three years ago now, I lost all my brake fluid in my system. Found my front driver side line was cracked and likely drained out the fluid. Replaced that line and I've never seen a change in the fluid level.

Driving 20 miles home with no brakes, now that's scary.