Should we substitute a lubricant for turboprop gear when OEM is unavailable?

[ScarlettJ]

I'm a newly licensed A&P mechanic working at a regional MRO, and I've been assigned my first major inspection on a turboprop's landing gear system. The manual calls for a specific torque sequence and a non-standard lubricant for the shock strut, but the shop's supply is out of that particular type. My lead is suggesting we use a common substitute, but I'm hesitant as it doesn't meet the exact OEM specification. In your experience with aircraft maintenance, how strict should we be about these specific material calls, especially on critical systems, and what's the proper protocol for a substitution when the specified part or fluid isn't available?