Hello folks,
I would like to introduce myself to the forum by writing something useful about hydraulic fluid.
A disclaimer to start with: I do not own a Crossfire, but I sure like them! I work for (and own) a company that rebuilds hydraulic cylinders, lines, and pumps for almost all modern convertibles. Since we are not yet sponsoring this forum, it wouldn't feel right to refer to our services in my posts until the moderators are comfortable with my contributions, and my posts are not regarded as SPAM. We are sponsoring several other forums already, and it can turn into quite a drain for a small company if one was to sponsor every forum that appeals to us. Thus, I'd like to hang out here for a while before taking the next step. Once we feel that the forum is generating enough business for us, we will be happy to become a sponsor...
The parts that are exposed to hydraulic fluid are the hydraulic cylinders, the hydraulic lines, and the hydraulic pump with the control valves attached. The hydraulic cylinders used in the Crossfire RST (Roadster Soft Top) are obviously quite similar to those used in some Mercedes convertibles. The hydraulic lines and the pump are modified versions of commonly manufactured parts, as well, made to fit your cars.
If you find that your hydraulic fluid level is not within the range shown on the reservoir (attached to the pump), then you have a leak somewhere (the fluid doesn't evaporate), and you have three things to do:
1) Find the leak.
2) Fix the leak.
3) Fill the fluid to the required level.
Correct me if I'm wrong, but it appears that Chrysler is specifying the following fluid for the top:
Pentosin CHF-11S. This is a good hydraulic fluid that is used also in some power steering and self-leveling systems. It can be purchased online in many places, or in some good auto parts stores.
Another fluid that is approved by Mercedes-Benz for systems with all the same materials in it as your Crossfires, is
FeBi 02615, along with Mercedes' own fluid p/n A
0009899103. It, too, is also used in power steering and self leveling systems. I would recommend this fluid for Crossfires without reservations. In fact, I recommend it to all of our customers. FeBi02615 is generally a bit cheaper than CHF11S, and the characteristics are practically identical. In Europe, the same fluid is also sold as
Aral Vitamol. I suspect that Aral is actually the manufacturer of the three fluids above. It is also sold under the brand name Weyle down under, with p/n 0009899103. These are all called "ZH-M" fluids.
What are the characteristics of a good hydraulic fluid for convertibles?
1) Low viscosity over a wide temperature range (meaning a thin fluid that is easily pumped through the tiny hydraulic lines and fittings even in cold weather). This requires a fairly refined product.
2) No Emulsifiers in the fluid. Emulsifiers would allow water to reach the seals in the cylinders and accelerate their chemical decay. Polyurethane gets "hydrolized" by water. Without emulsifiers in the fluid, any water from condensation will simply collect on the bottom of the reservoir without doing much harm, as long as it doesn't get sucked into the system.
3) Lubrication.
4) No additives that might attack the seals in the system. What might be a good additive for old-fashioned transmissions, is likely a nightmare for your hydraulic seals.
DO NOT used "Stop-Leak" type fluids or additives, as these will make those seals that haven't failed yet disintegrate all the faster. Stop-Leak makes the polyurethane seals in your OEM cylinders swell up at first, possibly seal the system for a short time, and then lead to catastrophic failure of all seals. If you buy new OEM cylinders from the dealer, their life span will be significantly shortened by the presence of such additives in the system.
DO NOT use brake fluid. Old-fashioned brake fluid attracts water. DOT5 brake fluid, which is silicone based, is theoretically okay, but it shouldn't be used in a system that already had oil in it.
I hope this helps,
Klaus