Hi John We have used Wurth additives now for many years! Many reps have come to us warning of the harm that solvent based flushes can cause!After 8 years of using solvent based,I can assure you that we haven't had a single problem.You have to be a bit sensible towards just what engines you can flush with it,EG:rattling cvh motors are a no-go!We have had a few detergent based left with us for free trials,but to be honest none of them even come close to the Wurth product!I can certainly recommend the use of engine flush in many of todays engines,especially multi-valve engines. But always remember to use top quality oils and filters after the flushing is done! Just my own oppinion, GUNNER!