By way of explanation, I bought a Rover mower at the local tip shop, seemed ok and with a basic service chugged along quite well. However, it has now fallen victim to the dreaded "not cleaning under the base syndrome" and has rusted out where the handles attach. I have a Masport base which takes the Rover catcher and is solid aluminum so set about swapping over. All good until the last of the bolts holding the engine decided not to come out. Rattle gun, heat, all the usual no avail until finally the head snapped. Had numerous older BS motors so got a oil pan housing off one of them (seems the same ( I hope) except for the oil drain, so it will have two oil fill points). Cleaning the replacement housing I was taken by the amount of sediment in it and thought a good service/rebuild would need to clean it out as it would contaminate any new oil and increase wear. It is fairly easy to get the housing off but the cost of replacement seals could blow the budget if done regularly, hence the silicon alternative. I agree with both of you, if the mower is relatively new, yes paper seal, but if the engine is old then silicon, as with the amount of gunk in the oil grinding the valve cam and crank seal they would be fairly sloppy. I will give the silicon a go and let you know how it went.
