modern hyd-rollers don't seem to care for the heavy syrup but if you can find a 20-50 with a cSt of 15 or less it'll work. it's no secret the industry has been moving toward lighter grade more importantly more easily flowing oils for decades. it should come as no surprise that the lifter manufacturers have answered the OEM's demand for lifters that work with their lighter thinner more easily flowing oils for better performance and fuel economy.
as George might say, Not Your Grandfather's Hydraulic Lifter