Have a spin on conversion/modification on one of my 235s and a cartridge drop in type on the other. For the amount of oil I am told they filter, I could live without them. One problem I have is determining how much oil to put in the crankcase with the filter. Calls for 5 quarts in the original manual but how much more do I need for the filter, surely not a quart. And is it best to put all of the oil, filter oil included, into the crankcase or put oil in the filter until it tops and then put the 5 quarts in the crankcase. I have been putting the whole amount in the crankcase and getting oil leaks at both ends of the block, because I presume only a small amount of oil is going to the filter and my oil pan is over full.
