Replacement for Fluid Drive fluid

[48_new_yorker]

I am trying to replicate, as exactly as possible, Chrysler (Chryco) Fluid Drive fluid which was originally used in the fluid coupling in my 1948 Chrysler New Yorker.

At present I am using "tractor hydraulic fluid" with an ISO of 32, but feel better performance could be obtained by using a hydraulic fluid that is closer to the original Chrysler Fluid which had ISO of approximately 25.

As best as I can determine, some key specs for the original fluid are as follows:

The fluid had a Viscosity Index of greater than 80.

It had a Saybolt Viscosity of between 100 and 150

It had an ISO of 25

The fluid had anti-foaming and anti-oxidation additives.

It specifically did NOT have any seal swelling agents as these can attack the carbon-graphite seal and the copper in the bellows.

Can anyone suggest a hydraulic fluid (by brand) or blend of compatible fluids that will meet these specs?

Also, can you suggest a place where I can purchase this BY THE QUART OR GALLON? I need only about two gallons max, so a 5 gallon quantity would leave me with way too much.

Thanks,
David in Santa Cruz

 

[roadrunner1]

my choice would be john deere hygard low vis. it has a iso 32 rating.
i have been using it in a marine gear (light duty) for at least 10 years with no issues, along with many hyd. systems.
i think the biggest advantage to this fluid in your app. is that its designed to be used in a wet clutch/wet brake app.
we have also used it in power steering apps. also with no issues

 

[2oldtommy]

Congrats on your restoration project of the '48 New Yorker! I had a '48 Highlander back in the day. You are correct that the carbon seal and the brass bellows in the seal must be dealt with carefully. I Don't have the answer for you, but suggest any Chrysler Clubs may help. Another would be CARS & PARTS magazine and their advertisers. IIRC the Gyromatic transmission itself requires a 10W motor oil. Lets have some pics when you can. If this is an original California car, that die-cast grill will require sun glasses to look at when the sun is out! FWIW--Oldtommy