QoS is the collective effect of service performance which determines the degree of satisfaction of a service. Since it is the collective effect of a service, it must have significant impact on the performance of routing protocols of any network. In MANET where the network has no fixed infrastructure and eventually the topology is continuously changing, QoS is a more challenging issue. However, the ability of a MANET to provide adequate quality of service (QoS) is limited by the ability of the underlying routing protocol and MANETpsilas QoS requirements can be quantified in terms of Packet Delivery Fraction, Average end-to-end delay of data packets and Normalized Routing Load. So, this paper, for the first time, presents the effect of data send rate, node velocity and transmission range on QoS parameters of the two contrasting MANET routing protocols OLSR and DYMO. These two protocols are simulated and compared with NS-2 under Gauss Markov mobility model. The simulation results show significant QoS performance differences.