Liqui-Moly Pro-Line Engine Flush

Every oil change removes old oil. It doesn't remove what the old oil left behind. Sludge, varnish, and deposits build up in lubrication galleries, oil screens, and the piston ring zone over time — and fresh oil going into a dirty engine isn't starting at full effectiveness. That's what this product is designed to fix.

The chemistry here is straightforward. The primary carrier is a hydrotreated light petroleum distillate — a very low viscosity solvent base that can reach areas your regular oil film doesn't fully penetrate. The SDS shows a kinematic viscosity of just 3.4 mm²/s at operating temperature, which is significantly thinner than any motor oil. That thinness is the point — it gets into tight passages and loosens what's stuck. The formulation also includes a zinc-based anti-wear compound and a calcium sulfonate detergent, both of which help suspend and move loosened contaminants toward the drain.

Independent testing has documented real results — compression restoration in cylinders that were running low, elimination of hydraulic lifter tapping, and waste oil coming out significantly darker and thicker than a standard drain, which tells you something was left behind that regular oil changes weren't removing.

One thing worth knowing — this product carries a DANGER classification on its SDS due to an aspiration hazard if swallowed. That sounds alarming but it's standard for petroleum solvent products. Handle it like you'd handle any shop chemical — don't ingest it, keep it away from your eyes, wash your hands after use. Normal shop behavior covers it completely.

Safe for use with turbochargers, catalytic converters, and diesel particulate filters (DPF/GPF). Does not attack common seal materials.

Not for: Motorcycles with wet clutches.

How to Use

Engine must be at normal operating temperature before you add it. Pour the full 500ml can directly into your existing engine oil — do not drain first. Let the engine idle for 10 to 15 minutes. Do not drive the vehicle or put the engine under load during this time. Then drain the oil and replace the filter immediately.

One optional step worth considering — some technicians follow up with a short interval cheap oil run, idling for another 10 minutes before doing the final quality oil fill. The reasoning is sound: the flush loosens a lot of material and a quick rinse cycle fully evacuates what's been disturbed before your good oil goes in. Not required, but if you're doing this on a high mileage engine with significant buildup it's worth the extra quart.

Who needs this: Anyone doing a serious maintenance reset on a high mileage engine. Vehicles with unknown service history. Engines showing signs of sludge, oil consumption issues, or sticky VVT solenoids. Anyone who wants their fresh oil working in a clean environment from the first mile.