Flushing additive ?
A friend of mine was on holiday recently down in the South of France and he came across someone flushing his engine using muffs but he also had a container (filter type thing) attached to the hose.
My friend asked what the mixture was but the language barrier got in the way and he couldnt understand the Frenchman, all he got from the conversation was that the additive was very important and everyone should use it.
Any ideas what the mixture could have been? ever heard of anything similar?