Oil additives and compositions

A fuel oil composition comprising a fuel oil and a wax growth arrestor additive composition, being an arrestor for said fuel oil, comprising:

• (a) an oil soluble ethylene copolymer having, in addition to units derived from ethylene, units of the formula
• --CH.sub.2 --CRR.sup.1 -- I
• and units of the formula
• --CH.sub.2 --CRR.sup.2 -- II
• the total proportion of units of the formulae I and II in the copolymer being within the range of from 7.5 to 35 molar percent, wherein each R independently represents H or CH.sub.3, and each R.sup.1 and R.sup.2 independently represents a group of the formula OOCR.sup.3, wherein each R.sup.3 independently represents a hydrocarbyl group having at most 8 carbon atoms, provided that the units of the formula I are different from the units of the formula II and, if formula I represents --CH.sub.2 --CH(OOCCH.sub.3)--, the molar proportion of units I is at least 5%, or
• (b) comprising
• (i) an oil-soluble wax growth arrestor ethylene copolymer being an arrestor for said fuel oil having, in addition to units derived from ethylene, from 7.5 to 35 molar per cent of units of the formula
• --CH.sub.2 --CRR.sup.1 -- I
• and (ii) an oil-soluble wax growth arrestor ethylene copolymer, being an arrestor for said fuel oil, having, in addition to units derived from ethylene, from 7.5 to 35 molar per cent of units of the formula
• --CH.sub.2 --CRR.sup.2 -- II
• wherein each R independently represents H or CH.sub.3, and each R.sup.1 and R.sup.2 independently represents a group of the formula COOR.sup.3 or OOCR.sup.3, wherein each R.sup.3 independently represents a hydrocarbyl group, provided that
• (A) when each of R.sup.1 and R.sup.2 represents OOCR.sup.3, copolymer (i) is an ethylene-vinyl acetate copolymer and/or a copolymer in which R.sup.3 is a linear alkyl group having 2 to 7 carbon atoms, and, in copolymer (ii), R.sup.3 represents a linear alkyl group having from 2 to 7 carbon atoms;
• (B) units of formula I differ from units of formula II;
• and
• (C) the number average molecular weights of components (i) and (ii) differ by not more than 2,000;
• with the proviso that additive (a) or (b) has a number average molecular weight of 2,000 to 5,500 and comprises at least one polymer made by saponification and re-esterification or by transesterification of an ethylene-vinyl acetate or propionate or an ethylene-methyl or ethyl meth(acrylate) copolymer.