In at least one embodiment, a process to produce a poly alpha-olefin (PAO) includes introducing a first alpha-olefin to a first catalyst system comprising activator and a metallocene compound into a continuous stirred tank reactor or a continuous tubular reactor under first reactor conditions to form a first reactor effluent. The first alpha-olefin is introduced to the reactor at a flow rate of about 100 g/hr or more. The first reactor effluent includes at least 60 wt % of PAO dimer and 40 wt % or less of higher oligomers, where the higher oligomers are oligomers that have a degree of polymerization of 3 or more. The process includes introducing the first reactor effluent and a second alpha-olefin to a second catalyst composition including an acid catalyst in a second reactor to form a second reactor effluent comprising PAO trimer.