Wynn’s Friction Proofing Professional Formula Advantages Wynn's Friction Proofing is professionally designed to be a multi-purpose crankcase additive that can be used in new and old engines, both petrol and diesel fuelled. Wynn's Friction Proofing is professionally formulated to provide the following benefits listed under each basic chemical ingredient. Wynn’s Friction Proofing is suitable for all petrol, LPG and diesel engines. Add entire contents of bottle of Wynn's Friction Proofing directly to the engine oil, with the engine turned off. Wynn's Friction Proofing is compatible with all commercial engine oils and is ideal for all normally aspirated or turbocharged engines.