The OFITE Roller Oven (U.S. Patent No. 4,677,843) is an effective aid in determining the effects of temperature on drilling fluid as it circulates through the well bore. The roller oven is designed to provide heating and rolling functionality simultaneously or independently. The 4-roller oven can hold six 260-mL Aging Cells or three 500-mL Aging Cells, while the 5-roller oven can hold twelve 260-mL Aging Cells or eight 500-mL Aging Cells.