In a temperate climate like UK there is no reason to use 0W oil at all (maybe in Siberian winter or Antarctic it would be more useful). 5W-30 or 10W-40 is more than adequate and cheaper as well. Don't get carried away with buying sports car super-synthetic oil for a Jazz, better to get a decent synth or semi-synth 5W-30 Ford A1 spec (fuel saver oil) for about £25. Just remember longer journeys are much better for your oil than short hops to the shops, and even if you only do 3K a year still change it every 12 months, not every 12K.