Oil filter info (Page 3/3) theogre JUN 07, 03:35 PM Flute # and design is not standard and never was for any car. And where dealing w/ ACDelco and some others... When the Contract goes out to Bid, the filters can and does change. If you find NOS parts can find several versions of "PF52" etc that can see changes just looking at them. Cup types may not work w/ all of them either. If you by current Fram then Same Cup made for that specific filter size years even decades ago often will still work. Buy other "Brands" w/ Fram base numbers, like xx3980yy or xx3387yy, often fits them too but may or not Purotator etc. depending just how the cup is made. (Number stay same letters before or after change for STP Wmart etc.) "Fram" cups even fit many ACDelco filters... Just tested w/ PF47 PH52E. But This is why "universal" cups often fail to grab many filters. I have some of these and nearly always fail to grab. My Unknown "I" cup and some others fit Fram at bottom of tool but also flatter Flutes on a "second lay" just above that. I have plastic "Universal" that claim to fit near everything but doesn't really fit any filter. Flutes likely gotten more "standard" only because there is a lot less competition between actual filter makers. "Fram" Co runs a batch of Fram, STP, Wmart, ACDelco PF52E and others and often just change paint and maybe filter cartridge inside....