[mikefocke]

Maybe the arguments for the filter adapter are:

Availability of cartridge filter
Cost of cartridge filter
Ease of replacement at any Jiffy Lube place once done
Removes fear of that plastic housing getting screwed on wrong or cracked on reinstallation
Better filter material in the spin on filters
No bypass allowing oil to escape filtration as can happen in the stock system
No need to clean out filter housing

And do these benefits outweigh the costs of the initial adapter and its installation? Too many variables for me to tell.

Is the every 3k miles I change the oil and filter guy gonna benefit? If he keeps the car for 10 years, that is 10 filters.

As one who had to go back 3 times because the local quick-oil place screwed up the filter replacement on a Honda...curiously they have never had problems with my Boxster's original cartridge.