The development of non-toxic, biodegradable vegetable oils as alternatives to petroleum derived quenchants and their influence on residual stresses and dimensional changes of AISI 4140 and AISI H13 modified C-ring steel test specimens is discussed. The C-ring test specimens were quenched in 6 different vegetable oil blends based on soybean oil and the results were compared to 2 different commercially available petroleum oil quenchants. Residual stresses were determined by X-ray analysis on cylindrical test specimens after quenching. Some measurements were also performed using the hole-drilling method to confirm the results obtained using X-ray analysis.