The fluid is definitly hydraulic fluid , When we got the car the tank was empty and our problems started when fluid was added. I don't know about the accumulators, my leak seems to be coming from the rubber hoses attached to the transfer case. I was told today that the hose set was $350. ouch. Does your car have a 4matic system? I am wondering if the two systems are interconnected. Too bad there is no good ol' Haynes Manual for this car!