The goal of the present study is to demonstrate 1H LF-NMR time relaxation measurements for efficient and rapid evaluation of Omega-3 polyunsaturated fatty acids (PUFA)-rich linseed oil (LSO) oxidative aging mechanisms, by monitoring primary chemical and structural changes occurring during thermal oxidative stress. The LF NMR monitors the different proton spin-spin coupling energy relaxation times, T2 within LSO molecular segments, from the initiation of free radical generation and hydroperoxide formation to the propagation of alkoxy radicals, and alpha, beta-unsaturated aldehydes formation, and a termination phase of crosslinked polymerization end products. The 1H LF NMR T2 values monitors both the covalent and secondary bonding interactions (e.g., electrostatic and hydrogen bonding) during the different oxidation phases. The present paper shows that LSO tail segments mobility in terms of T2 multi-exponential relaxation decays, generated by data reconstructing of 1H transversal relaxation components are providing a clear, sharp and informative understanding of LSO sample’s autoxidation aging processes. This is supported by high field band selective 1H NMR pulse excitation for hydroperoxide and aldehydes quantification of the same LSO samples at 25, 40, 60, 80, 100, and 120oC with pumped air for 168 h. Peroxide value, viscosity and self-diffusion, as well as fatty acids profile and by- products determined by GC-MS were also carried out, and correlated with the LSO tail T2 relaxation results. In conclusion the selective determination of LSO alkyl tail T2 energy relaxation time domain values was demonstrated as a rapid evaluation marker for following omega-3 PUFA-rich oils oxidative aging.