Renew oil filter housing liner
In order to ensure a perfect seal of the 4mm o-ring of the oil filter a gap of 3.2 to 3.8mm should be kept to the housing. If this distance is larger, the filter housing liner has moved to the rear.
The original tube does not seat at the rear of the housing and for /6 and /7 models it has a sharp edge!
Our modified tube is longer - we measure the housing and shorten the tube to the required length and seat it to the rear of the housing.
Remove liner, measure housing and fit liner - based on receipt of clean engine housing - or within any engine overhaul.