Well, everyone seems to have firm ideas about it. I'll be on the watch for a suitable replacement, so far no problems.

With respect to oil vs silicone refill, I should have pointed out that I used what was available, some have used hydraulic jack oil, etc. Any oil will help an "empty" viscous clutch have some coupling and work to a degree. Silicone oil of the proper type will have the best operation. Going the other way, some oners have also drilled a couple of screws through the fan clutch, making it a 100% coupling. This hurts mpg, may work in a low speed driving area like a congested city; and certainly would have problems at high rpm.

__________________
91 300 TE 235K
93 Cabriolet 155K sold
92 300 TE 200K boneyard

Here is an alternative.
http://www.peachparts.com/shopforum/diesel-discussion/106150-bye-bye-fan-clutch.html#post729992



.

__________________
ASE Master Mechanic
https://whunter.carrd.co/

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
2003 Volvo V70

https://www.boldegoist.com/