I've just become the proud owner of a Lister SR3 engine in my narrowboat. The only manual I've been able to get hold of is the Parts List which is very interesting. My first problem is, at how many hours should I change the engine and gearbox oil? Can someone tell me the capacities, and are these the correct grades - engine SAE 20CC and gearbox SAE 80. Looking forward to reading any replies. Thanks, Pop.