buster205 0 Posted March 15, 2010 Hi all unsure what octane fuel i should be using, i've got a 1991 1.9 gti which as had the head and block changed for xu9ja/z items, i.e lower comp ratio but all other components are from original xu9ja engine, does the c.r. and head determine octane required or management system ? cheers Ste Share this post Link to post Share on other sites
2-Pugs 57 Posted March 16, 2010 If you effectively have an XU9JAZ engine then any unleaded grade should be fine Share this post Link to post Share on other sites
