The 8891-320 uses 2.9 gal. (11 liters) Silicone Oil, part number 5-1070-x.
Depending on availability, you can order the oil coolant in a variety of sizes:
|Part Number of Silicone Oil||Container Size|
For convenience, Bird offers various maintenance kits for the 8890 series that includes the silicone oil here: 8890 Series Repair & Maintenance Kits.
Please see the Material Safety Data Sheet (SDS) for further information: Silicone Oil SDS