Strippage

[Dan!]

That can't save 20kg?! You wouldn't use 20 litres of underseal to do a car would you? I must of used 1 or 2 to do mine

Remember underseal is thicker than water though, so its not 1kg per 1 litre

2.5L of Waxoyl weighs around 4.5kg according to here - Link

And when you scrape the underseal off you'l realise how thick they apply it from factory, probably alot thicker than you did when you did it. Wouldn't surprise me at all if they used 10L doing the whole underside of a car.