IOTA BJ510 Polyphenylmethyldimethylsiloxane is your go-to for pressure transfer in remote thermostats. This silicone fluid is clear, stable, and compatible with various solvents. Not suitable for medical use, it excels in low-temp applications and has a usable life of 60 months when stored properly.
IOTA BJ510 Polyphenylmethyldimethylsiloxane-IOTA (phenylsilicone.com)