BIZOL Oil System Clean+ o90 is an engine oil additive Made in Germany especially developed for the maintenance of the entire oil system. Highly effective cleaning agents dissolve soot, varnish and deposits on all surfaces, including hydraulic tappet, in the engine. All deposits are removed without affecting seals or gaskets by draining the used oil. BIZOL Oil System Clean+ o90 prepares the oil system for an optimum performance of the fresh engine oil. Cleaning the oil system with this product will increase compression and restore the elasticity of o-ring seal. Improved compression reduces exhaust gases and thereby protects the catalytic converter and DPF. This results into a noticeably smoother engine run and increased operational reliability.