check ams oil http://www.amsoiluk.com/
they have good products. not heard here in UK more because its an american product. WE have used it for lona time and performance car even..the bad thing in UK is that less product to chose and not alot of places to buy. But in comes to engine oil fully synthetic will run for 25,000 orr ((30,000 if you use there oil filter). they have also the fuel additive which is good for 4,000 to clean the engine etc which in turn gives you a better milleage. but check the products. expensive but worth it.. let me know