Ok to mix, but draining as much as you can by the master cly reservoir, then
moving to a high quality fluid will surely be best process.

I've switched to Pentosin DOT 4LV, PEN-1224116  (retails for around $15 (1
Liter)

Product Information
DOT 4 brake fluid
Low viscosity DOT4 brake fluid

Pentosin DOT 4 LV is a special brake fluid of highest DOT 4 performance
levels and extremely low viscosity at cold temperatures. It offers safety
against vapor lock; it has excellent resistance to absorbing and retaining
water and provides superior corrosion resistance. Pentosin DOT 4 LV Brake
Fluid is ideal for all modern vehicles with ESP and ABS. DOT 4 LV can be
used in all vehicles that require DOT 4 fluid.

Product attributes:
- Appearance: Yellow & Clear - Density at 20�C: 1062 kg/m� - Kinematic
viscosity at 40�C: 6.4 mm�/s - Kinematic viscosity at -40�C: < 700 mm�/s -
Melting point: >-50�C/ >-58�F - Flash point: >130�C/ >266�F - Ignition
temperature: >200�C/ >392�F - Boiling point: >265�C/ >509�F - Wet boiling
point: >170�C/ >338�F - pH Value: Slightly alkaline

Very pleased with performance, and subsequent fluid flushes are much
cleaner.

If you drive it the mountains, or heavy traffic in warmer climates, you may
want to consider ATE-706202, also DOT4 
Typ 200 specifications:
Dry boiling point: 280�C (536�F)
Wet boiling point: 198�C (388�F)
Recommended change interval: Up to 3 years  (personally I'd never go more
than 2 years)

Modern brake fluids are glycol based and comply with DOT3, DOT4, or DOT5.1
standards. Glycol based fluids are hygroscopic which means they absorb
moisture. Additives in brake fluids are designed to prevent corrosion caused
by moisture. Simply put, the longer you keep brake fluid in your system the
higher its moisture content will become. A higher moisture content decreases
the boiling point of your brake fluid and increases the temperature at which
the fluid will freeze.

Jack

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Mike Griffiths
Sent: Tuesday, February 1, 2022 4:53 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Brake fluid

Can you  mix DOT 3 and 4?