A method for producing heavy oil, the method including testing a plurality of samples either from a reservoir play or simulating a reservoir play in a temperature and pressure controlled gravity drainage experiment. Test injection fluids are injected into the samples at a reservoir temperature and pressure and Cumulative Oil Production (COP) or Recovery Factor (RF) or similar feature measured over time. An injection profile is obtained by selecting n injection fluids based on a best COP or RF at a given time Tn, wherein n is a number of fluid injection stages and switching to an n+1 injection fluid when a rate of change (ROC) in the COP or RF drops at least 25%-75%, but preferably 40-60% or 50%. The injection profile is then implemented in the reservoir to produce heavy oil. Optimized injection profiles for certain reservoirs are also provided.