right lads what oil should i be using in my standard frst. there are many myths out there in the haynes it says "multigrade 5W/50 - 10W/30" and this site says " full synthetic oil mobil 1 15W/50 OR CASTROL RS 10W/60

what woul you sudjest as i want to maintain mine every 3000 miles or so

any thoughts would be appreciated!!!