I put my Mercruiser 4.3 EFI in for a service to have the thermostat replaced, an overheating problem looked at and a starter motor replaced along with the usual service. When I got the boat back, after running for a couple of hours I had a pint of oil in the bilge. Back to workshop where they told me hoses to/from oil filter were weeping so they were replaced for more $$$. After a couple of hours running I had about 1-2 pints of oil in the bilge again. Workshop claim that nothing they have done could have caused the oil leak. Question is, is it just coincidence that oil leak started after service or could they have done something and also any suggestions where oil is coming from. There is no leak obvious so must be low down on the engine.
