B3C Mechanic In A Bottle Petrol Test Swabs Pack of 5Mechanic In A Bottle Petrol Test Swabs provide a quick and easy means to test your petrol, taking just a few minutes; they provide a visual indication as to the condition, be it Fresh, Marginal, or Bad.The Mechanic In A Bottle Petrol Test Swabs are part of the multi award winning family of fuel solution products from B3C. This product range is scientifically engineered to provide a quick, easy, and effective means to TEST – FIX – PREVENT the problems associated with modern day fuels. Application: The Mechanic In A Bottle Petrol Test Swab provides a quick and easy means to test your petrol, taking just a few minutes; they provide a visual indication as to the condition, be it Fresh, Marginal, or Bad. Currently in the UK; unleaded fuel can contain up-to 15% ethanol. Ethanol is Hydroscopic, (meaning that it attracts atmospheric moisture). If ethanol and water are mixed together it becomes corrosive to rubber and metal components. It has been found that one of the side effects of ethanol fuel is that it can cause degradation of fuel filters, resulting in small particles of the filter being carried into the carburettor and causing running issues and the constant need to adjust the carburettor. This simple test allows you to check if your fuel is still fresh (low moisture content from absorption of atmospheric moisture).Directions: Step 1: Submerge swab into the fuel for 5 seconds. Step 2: Shake swab; let dry for 2-3 minutes. (Do not exceed minutes)Step 3: Compare to petrol test Chart. (Indicator colour takes several more minutes to develop for 2-Stroke mixed fuel).