Condensates

A method of improving the thermal stability and/or the water tolerance properties of a fuel or lubricating composition which comprises using as an additive a cyclic compound comprising m units of the formula Ia:

• and n units of the formula (Ib):
• joined together to form a ring,
• wherein Y and Y2 are divalent bridging groups which may be the same or different in each unit;
• R0 is H or (C1-C6) alkyl or is a metal or ammonium cation;
• R5 is H or (C1-C60) alkyl or OH group;
• J is 1 or 2;
• R3 is hydrogen, a hydrocarbyl or a hetero-substituted hydrocarbyl group;
• each of R1, R2 and R4, which may be the same or different, is hydroxyl, hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl, with the provisos that
• i) at least one of R1, R2 and R4 is hydroxyl, and m+n is 4 to 20, m is 1-8 and n is at least 3, and
• ii) in formula Ia at least one OH group is in the meta or para position to the COOR0 group and/or at least one R5 group is OH.