Desperate to find Convertible Top Fluid?

I am repairing a leaking seal on the hydraulic cylinders for my 66 Coronet convertible top. The system has lost most of its fluid. I have asked a number of people what fluid goes back in the system and I have had all kinds of answers from ATF, to brake fluid, to light hydraulic fluid from Caterpillar. Does anyone know for certain what I should put in this thing, where I can get it and what the system capacity is? Thanks.

My 1970 Mopar service manual says to use "AQ-ATF Suffix A Dexron type transmission fluid". I imagine not much changed between 67 and 70 on the hardware (or liquidware, if you like). That is a start - I have no idea if anything better has been found in the last 39 years, though. It doesn't say what the capacity is, but it does say how to fill it and purge it of air. E-mail me if you want me to scan and send the page. Good luck!

My 66 Dart convert takes regular old ATF......

My 1970 Mopar service manual says to use "AQ-ATF Suffix A Dexron type transmission fluid". I imagine not much changed between 67 and 70 on the hardware (or liquidware, if you like). That is a start - I have no idea if anything better has been found in the last 39 years, though. It doesn't say what the capacity is, but it does say how to fill it and purge it of air. E-mail me if you want me to scan and send the page. Good luck!

I thought this thing might use ATF, but someone on another forum indicated that the specs changed around 1966. Very frustrating.

My 69 uses Auto. Trans. Fluid too.

Ditto on the tranny fluid

Unless it says otherwise I'm pretty sure all the convertibles of the era use the same fluid, especially since the hydraulics look strikingly familiar between the different car makes. Type A is what goes in my buddies Firebird and I think that fluid contains (or used to contain) whale oil. I believe Dexron replaced type A. According to my Parker O-ring book seal compatibility between the two fluids is close. No silicone, EPDM or neoprene to name a few. The more familiar elastomers Nitrile NBR (buna N) and Fluorocarbon (Viton) are OK between the two types of fluid. Sounds to me you can drain and flush and just use Dexron.

all hydraulics will work with atf. i,d bet dex4 would be overkill. Please dont quote me on this i,m not a tech but have made do with different fluids in equipment in the field. i was always told atf was hydraulic fluid with additives. and hydraulic fluid was just a light oil with additives.