Petroleum Distillate Aliphatic

Petroleum Distillate Aliphatic (CAS 68476-34-6) is a heavy paraffinic petroleum fraction used as the primary degreasing solvent in classic mechanic-grade engine cleaners. The chemistry is straightforward: motor oil is a petroleum hydrocarbon, so a refined petroleum hydrocarbon dissolves it on contact. This is the reason traditional engine degreasers cut baked-on grease faster than water-based alkaline alternatives, and the reason they cannot be reformulated to be "eco-friendly" without losing performance.

The ingredient appears on California's Safer Consumer Products Candidate Chemicals List (Cal. Code Regs, tit. 22, §69502.3), and is treated as a VOC under EPA 40 CFR 59 consumer-product rules. At high concentrations (60–70% of a formulation) it drives the parent mixture's aspiration-hazard, STOT RE, and high-VOC classifications. ACGIH carries a skin designation, meaning dermal absorption is a meaningful exposure route — not just inhalation and aspiration.

For users: gloves and outdoor application are non-negotiable when the formulation runs this hydrocarbon at heavy-duty solvent concentrations. The combination of H304 aspiration risk and ACGIH skin designation means casual rag-wipe with bare hands is the wrong way to use a product built on this chemistry.