May be involved in the final steps of cholesterol and steroid degradation (PubMed:28377529). Catalyzes the formation of 4-methyl-5-oxo-octanedioyl-CoA (MOODA-CoA) and acetyl-CoA from 6-methyl-3,7-dioxodecanedioyl-CoA (MeDODA-CoA) and coenzyme A (Probable). acetyl-CoA + an acyl-CoA = a 3-oxoacyl-CoA + CoA 6-methyl-3,7-dioxodecanedioyl-CoA + CoA = 4-methyl-5-oxo-octanedioyl-CoA + acetyl-CoA kcat is 4.8 sec(-1) with acetoacetyl-CoA as substrate. Steroid metabolism; cholesterol degradation. Turnover of MeDODA-CoA is low and FadA6 may not be the physiological thiolase responsible for MOODA-CoA formation. Belongs to the thiolase-like superfamily. Thiolase family. Truncated N-terminus.