Experimental temperature data for a new precipitation detection technique based on heat transfer through a precipitate layer are presented. The fully automated technique requires only 39 h to determine the solvent/bitumen ratio at which asphaltene precipitation begins. Precipitation of n-heptane asphaltenes from Cold Lake bitumen was found to begin at a solvent/bitumen ratio of 1.5. Using this detection technique, a number of aromatic compounds, compounds with N, S and O heteroatoms and hydrogen donor solvents, chosen for their similarity to resins, were tested for their ability to delay the onset of asphaltene precipitation. Phenanthrene was found to be the most effective additive, and the compounds containing nitrogen the least effective.