The invention relates to a method for producing Mannich adducts that contain polyisobutylene phenol by: a) alkylating a phenol with highly-reactive polyisobutylene at a temperature lower than approximately 50 °C and in the presence of an alkylation catalyst; b) reacting the reaction product from a) with formaldehyde, an oligomer or with a polymer of the formaldehyde and with at least one amine, which has at least one secondary amino function and does not have any primary amino function; or c) reacting the reaction product from a) with at least one adduct consisting of at least one amine, which has at least one secondary or primary amino function, and with formaldehyde, an oligomer of the formaldehyde, a polymer of the formaldehyde or with a formaldehyde equivalent. The invention also relates to Mannich adducts that can be obtained by using this method, to the use of the Mannich adducts as detergent additives in fuel compositions and lubricant compositions, and to additive concentrates, fuel compositions and lubricant compositions containing these Mannich adducts.