W126 which brake fluid
 

Which brake fluid do I use on a 83 380 SEL?

Any DOT 4. I like Castrol LMA.

Duke

Look at your owner's manual. But like Duke said, DOT 4 is what you need. Any brand will do. Just a litlle FYI the "4" versus a "3" (DOT 3) is a temp rating. DOT 4 can handle temperatures higher than 3. Off the top of my head I can't remember the temp. ranges but 4 is better. However, even though there is a DOT 5 out there, you can't use it on your car. DOT 5 is silicone based, and shouldn't used in your car's brake system.

OK thanks guys. So dot 4? I have a bottle of dot 3 in my garage can I use that?

fluid
 

you can use it, it wont hurt to mix dot 3 and dot 4. i personally wouldn't do it, the dot 4 has a higher boiling point than the dot 3