If your open to other options I'd highly recommend britemax vantage. Its the easiest wax I've ever used, spreads really nice and is even easier to remove.
All three of these products in the link are brilliant and at this price offer good value for money. I honestly think my clio looks its best after blackmax and vantage.
My bottle of 845 just sits on the shelf now I've got vantage (845 is amazing for £15 tho) and sometimes I would rather use vantage over my autofinesse passion which costs a lot more when you consider the price of this kit.
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Only problem is its not on amazon at that price.
If you do get 845 just give it a shake like Adam said also if you leave it in the garage or shed and it gets cold warm it up a bit.
For the price 845 is brilliant!