Leaks between the oil sump and the oil cooler are often due to worn seals. These seals should not be given a second life, and should be replaced as soon as they are removed.
In the 70s and 80s, if the oil cooler had to be replaced and your Volkswagen was pre-7.1969, a post-8.1969 oil cooler was used, i.e. an oil cooler with 10 mm oil channels instead of the 8 mm required from the factory. To compensate for the difference in diameter, leakage seals have been used. So always check the diameter of your oil cooler and that of the crankcase, and buy leakage gaskets if necessary. These are listed in the "other models" tab.
On CT/CZ 1600 cc engines, which are exclusive to VW Vanagon models, there are rubber seals between the oil cooler and the flange, and a paper seal between the flange and the crankcase. This differs from all other engines, where only rubber gaskets are used.
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