brake fluid topup...

[777Dave]

My airplane was finished about 20 years ago by someone other than me. Doing my annual and for the first time it looks like the reservoir needs a bit of fluid. I can see that what has been used is red (ATF?) Anyone got a suggestion as to what was likely used and therefore what I should add?
I have had no obvious leaks so far.

Thanks

[Ron B.]

I would guess it's MIL-H-5606. Aircraft brake fluid and available from ACS.
Ron

[aerhed]

MIL 5606 is red. Most common brake fluid out there.

[lostpilot28]

ATF looks just like 5606, so be careful. I'm not sure they're compatible, and I would guess they are not. I do believe they are both safe for your seals in your braking system, so flushing it out and putting either in is probably the safest bet.

Then again, maybe you should contact the previous owner and ask them what it was.

[777Dave]

Appreciate the responses.