First time poster, I apologize if this inquiry is in the wrong location- feel free to move it.

I'm currently using Silicone Oil as a viscous fluid in an application to control speed through an adjustable valve. The device needs to function at temperatures from approximately 15C-25C so the VI of the fluid is important to ensure that the speed characteristics remain similar at 15C and 25C. The VI of our current Silicone Oil is 518 (Kinematic Viscosity of 1600mm^2/sec @ 40C, 648mm^2/sec @ 100C). Obviously this isn't too bad but I was wondering if there are any other oils/fluids out there with a higher VI?

Thanks for your time,