HVI hydraulic oil 55 gal - $495.00 - Free Shipping | HVI-46 Grade Hydraulic fluidThis is a High Viscosity Index (HVI), mineral based hydraulic fluid which means it can continue to flow at very cold temperatures. They also have a high Dielectric Strength which mean they resist the flow of electrical current. That is why they are the preferred hydraulic fluid for use in Electrical Bucket Trucks.