step solely as a molecular weight control agent sauer et al teach the subsequent hydrogenation of their very low molecular weight oligomers to produce a desired saturated product it is a distinct benefit to the process of this invention to produce substantially saturated oligomers as a product of the oligomerization step without the need for a second stage or subsequent hydrogenation step the oligomerization pressure is suitable from about 1 to about 175 atmospheres preferably from about 5 to about 25 atmospheres total pressure if hydrogen is used as the molecular weight regulator suitable hydrogen partial pressures can be from about 1 to about 158 psig 1 to about 11 75 atmospheres preferably from about 60 to about 120 psig 4 08 to about 8 13 atmospheres as noted above an added advantage of the process of this invention is that a substantially fully saturated product can be obtained which does not require post hydrogenation the obtention of this substantially fully saturated product is a function of the particular catalyst employed the catalyst concentration and other reaction conditions for example when the catalyst employed is diisobutyl aluminum hydride the use of a relatively low partial pressure of hydrogen of 100 psig resulted not only in the use of hydrogen as a molecular weight control agent but also in the production of a substantially fully saturated product that is one having a bromine index of less than about 500 higher hydrogen partial pressures within the range noted above may be required with other catalysts to produce a substantially saturated oligomer product in one step additionally it has been found that there is some saturation of the alpha olefin feed during the oligomerization process conducted in the presence of hydrogen the unconverted feed which usually contains from.