Comma X-Flow Flush Out (XFFO5L) Mineral Engine Oil Flush - 5 Litres 5L. This is a traditional flushing oil suitable for both petrol and diesel engines. It works by improving engine performance by removing sludge and carbon deposits. The product comes in a 5 litre container. Comma Oil & Chemicals Ltd is a world class manufacturer and supplier of automotive lubricants, chemicals and ancillaries.