So this stuff is really good. It has some long boring name like Terraclean Extended boring blah whatever. I call it Terrajuice. What it does is really cleans out the engine when having an oil change, not like just draining oil but breaks down all the sludgy crap built up in the galleries and feed pipes etc. Now I have been in this business a good while and seen all manner of products come and go, but literally everything from Terraclean is bang on the money. I try and always steer customers in the direction of what is most cost effective and beneficial for them and that has kept us in business for a long time, its one of our only publishable company mottos - Don't sell crap or talk shite!
Anyway this stuff, anyone who has a service at the same time as a Terraclean gets the Terrajuice treatment for free, usually £19.99. And in my eyes its a blinding product designed to keep your engine healthy for longer. Like a colonic for the lubrication system