I think they have a gorilla at Onan installing the original filters!
This is my second 5500, and both original filters were really snugged down. I tried the socket type, and it just rounded off the filter. Had to use a strap wrench with a screwdriver shim to get 'em off.
After the original, they've been easy.
Don't forget to "charge" the filter before you install it. It'll cut install time in half. The oil goes in really slow, anyway, but worse with a dry filter.
2005 Georgetown 342DS XL, Full Banks Package
2005 Liberty Renegade 4X Toad
1989 Wrangler Sahara Toad
1984 19.5' Beachcraft i/o 5.o liter, 4-bbl (and you thought your Moho sucked gas!)
D/W Carole and Maggie the Teacup Lab (Black Chihuahua)