An experimental studies of the performance of a heat pump are conducted to cover the effect of oil flooding, oil cooling and type of expansion devices. These studies show that there is an improvement in the performance factor with oil addition up to 9.2% for capillary tube and 8.6% for thermal expansion valve. The performance improvement is combined with decreasing power consumption of the system by 2% and 2.5% for capillary tube and thermal expansion valve respectively, in comparison to the standard case. The cooling of oil also improved the performance factor for the thermal expansion valve by 4.3% and 3.2% for natural and forced cooling respectively. There is also decrease in power consumption of the system by 2.6% and 4.9% for the above cases. However, using capillary tube with two way of oil cooling cause a decrease of the performance by 6.6% and increase in the power consumption by 9.5% and 3.4% respectively for natural and forced oil cooling. It can be concluded that the use of capillary tube with oil addition, led to better performance factor than the thermal expansion valve with no cooling of oil. Conversely with oil cooling by natural and forced the thermal expansion valve has better performance factor.