Use of polynuclear phenolic compounds as stabilisers

A method comprising adding at least one polycyclic phenolic compound in light, oxygen and/or heat stabilizing amounts to a mineral oil-based product or fuel in need of light, oxygen and/or heat stabilization, wherein said at least one polycyclic phenolic compound comprises from 3 to 20 benzene rings per molecule and is obtained by a process comprising reacting a tetrahydrobenzoxazine of the general formula I

• in which the substituent R1 is a hydrocarbyl radical which has from 1 to 3000 carbon atoms and may be interrupted by one or more heteroatoms from the group of O and S and/or by one or more NR6 moieties,
• where R6 is a hydrogen atom or a C1- to C4-alkyl radical, and
• in which the substituents R2, R3, R4 and R5 are each independently hydrogen atoms, hydroxyl groups or hydrocarbyl radicals which have in each case from 1 to 3000 carbon atoms and may be interrupted by one or more heteroatoms from the group of O and S and/or by one or more NR6 moieties, where R6 is as defined above,
• with one or more of the same or different phenols of the general formula II
• in which the substituents R7, R8, R9 and R10 are each independently hydrogen atoms, hydroxyl groups or hydrocarbyl radicals which have in each case from 1 to 3000 carbon atoms and may be interrupted by one or more heteroatoms from the group of O and S and/or by one or more NR6 moieties, where R6 is as defined above,
• and/or with one or more of the same or different tetrahydrobenzoxazines of the general formula I,
• where the substituent R4 may also be a radical of the formula Z and the substituent R9 may also be a radical of the formula Z′
• in which the substituents R1, R2, R3, R5, R7, R8 and R10are each as defined above, the substituent R7 may also be a radical derived from a tetrahydrobenzoxazine of the general formula I, the substituent R15 is hydrogen or a radical derived from a tetrahydrobenzoxazine of the general formula I, and the substituents R11 and R12 may be the same or different and are each hydrogen or a C1- to C1O-alkyl radical,
• and in which the substituents R2 and R3 or R3 and R4 or R4 and R5, together with the substructure —O—CH213 NR13—CH2— attached to the benzene ring, may also form a second tetrahydrooxazine ring, or the substituents R2 and R3 and R4 and R5, together with the substructures —O—CH2—NR13—CH2— and —O—CH2—NR14—CH2— attached to the benzene ring, may also form a second and a third tetrahydrooxazine ring, where R13 and R14 are each independently hydrocarbyl radicals which have in each case from 1 to 3000 carbon atoms and may be interrupted by one or more heteroatoms from the group of O and S and/or by one or more NR6 moieties, where R6 is as defined above,
• with the proviso that at least one of the substituents R1, R2, R3, R4, R5R7, R8, R9, R10, R13 or R14 is a polyisobutenyl radical having a number-average molecular weight Mn of from 183 to 42 000, and the remaining substituents from the group of R1, R2, R3, R4, R5, R7, R8, R9, R 10, R 13 , or R14, when they are hydrocarbyl radicals, each have from 1 to 20 carbon atoms.