My 1978 Tolly 48 has two CAT 3208 N/A engines installed. Each engine has two oil filters, mounted upside down on a common mounting base. Am I correct in assuming, once the engine has shut down, that the oil contained in each filter drains back into the sump? If not, how in the heck do you remove the filter(s) without dumping a quart or so of dirty oil all over the engine? And I am familiar with the trick of poking a hole in the top of the filter can, to ensure there is no vacuum holding oil into the filter, prior to unscrewing it. But just not sure how else to ensure the filters' are empty prior to removal.
And the obvious related question-I presume if the filters are NOT full at startup, as the oil has drained back into the crankcase, that I don't have to pre-fill the new filters prior to installation.
Note that my engine manual seems to be somewhat generic (not marine specific, for instance) in that it shows only a single filter, mounted upright on a side-hung bracket. Not at all like my installation.