Real time neutron imaging has been found to be particularly useful in studies of dynamic phenomena of internal combustion engine systems. (1, 2) A real time neutron imaging system has been developed at the University of Michigan Phoenix Memorial Laboratory (PML). Using this device certain materials such as hydrogen containing substances, which have a high thermal neutron cross-section can be imaged inside materials such as aluminum and iron which have relatively low thermal neutron cross-sections. The use of real time neutron radiography therefore allows the dynamic imaging of hydrogenous substances (oil, diesel fuel, gasoline, water, etc.) inside metal objects such as internal combustion engines. Using computerized image enhancement techniques, quantitative determination of the density, presence, or absence of various lubricants and fuel sprays can be made.