The 245R type of filter is a spin-on ... the cartridge spins onto the filter 'head' and the clear plastic 'sump' spins-on to the filter cartridge. All you need is a 'strap wrench' and means to collect the spilled oil when you remove the old cartridge. Example:Strap Wrench from RIDGID | The Home Depot - Model 31340
The typical engine guard filter cartridge (from an automotive supply) is Wix #33262 .... or equiv. and is 19然 nominal rating.
For other filters for this engine: WIX filters, WIX oil filters, WIX air filters, WIX fuel filters, WIX Heavy Duty Oil Filters : Filter Look-Up
---> offhighway ---> marine ---> etc. simply take these numbers to your auto parts store and they will have (usually special order) these filters availalbe from various mfgrs. .... and at MUCH lower prices than from a 'marine source'. Yanmar does not 'make' filters, they buy them from automotive filter mfgrs. ... and then apply a hefty 'markup'.
Yanmar filter arrangements are usually: 30然 (primary) ----> 10然 (secondary) ----> 15-19然 (engine guard - small cartridge in housing).
Depending on the operating history of your fuel tank and usual fuel supply and the 'relative cleanliness' of your tank ... the 30然 may or may not be needed. If the present 'first' filter in the sequence has a lot of 'visible' debris (sand, rust, visible particles) on the 'upstream sided' of the pleat surfaces then you need to 'prefilter' the oil with an additional (sometimes called a 'primary') filter upstream of the normal 10然 filter in the fuel delivery system. If you have installed vacuum gages and have recorded the gage readings over time you will know how well these filters are removing debris and know when to add such a 'prefilter'.
A clean tank with clean oil usually doesnt need the 30然 ... the vacuum gage on the 10然 will usually validate that need.
The small engine mounted 15-19然 is there solely to protect the engine in case one of the 'upstream' filters (30然 or 10然) fails and releases a massive amount of particles to the engine --- a 'last chance filter'.