General purpose Immersion oil.  

Higher Viscosity version of Type A

Refractive Index @ 23° C:
F Line (486.1 nm) - 1.5236
e Line (546.1 nm) - 1.5180
D Line (589.3 nm) - 1.5150
C Line (656.3 nm) - 1.5116
Viscosity: 1250 cSt ± 10% @ 23°C (High)