Red is home heating oil. They dye it red so they can tell if you are running it in your vehicle. Most private citizens don't have to worry, it is if you are a commercial outfit and get caught that it can be bad.

HSMO is NOT Z-HM
 

After reading a few threads on Benz hydraulic suspension systems, I realized the PO of my car had screwed up yet again.

When I was looking at the car I noticed that the SLS hydraulic fluid tank was empty, so I asked the feller (a mechanic) what was going on. He said he'd forgotten to fill it after the last time he worked on the car (about a year ago when it was parked) and handed me a couple liters of Castrol HSMO (Hydraulic System Mineral Oil) he had in stock - stuff used by Jaguar, Rolls & Bentley hydraulic suspensions. Not knowing any better and trusting him (HA!), I poured them in, bled the system with some help from a couple big guys who were standing around to act as ballast and everything seemed OK.

Of course, now I find out that HSMO is mineral based (like baby oil) and Z-HM is hydrocarbon. All they have in common is that they are green. Now I get to drain and flush the SLS system too! Yay!!!

Here's a link about Citroen hydraulic fluids. There's an interesting table comparing viscosity of various hydraulic fluids at different temperatures.

http://www.candokaraoke.com/tony.html

Off-highway fuel. Common in farm and construction equipment.

- Jeff
'87 190Dt
'87 300Dt

For a few weeks after hurricane Katrina, it was legal to use the red stuff.