Hi Bill , re the oil I buy mine from Merseymotor cycles on Regent Rd Bootle ,£19 x 5 ltrs is a much better price than the £36 quoted by another local shop which is also a Royal Enfield dealer . At that price I think you could drain , fill and run it for a time then change again all for what you could have paid anyway plus you'll have peace of mind knowing the oils fine . Sounds perdantic but I'd take the tank off first ,clean out completely ,has per previous posts, reinstall fill run and then take it off again and clean it out again, that way you'll see just how clean or not the inside is ,regards BobH ps no association with the named shop.