So where should I locate the littler box

I picked up the senior cat attract cat litter and was thinking of scrubbing the garage floor in the region were Ox uses it as a bathroom and then placing the litter box in that area???

Or should I scrub that area and place it somewhere else in the garage???

Well IMO if you are putting a car in the garage, the cat may not want to even use the pan because its not quiet and private. And if your cat is not allowed outside, having the litter pan in the garage will increase the chance of the cat escaping out of the house.

Usually people put the pan in the bathroom, an unsued bedroom, or the basement.

option number 1 scrubbing the garage floor in the region were Ox uses it as a bathroom

Just because it makes sense in my human mind to do that, but I have know idea how those little kitties brains work, he may just decide to use another part of your garage....

Well right now he is in the house but he spends most of his time in the garage or sunning himself outside (trust me he doesn't go far nowadays.) He is 18.5 yrs young.

If he used the garage as a bathroom he does it overnight and usually in the same spot.

He spends the winters in the house but with not using a litterbox in many many years I want to see if this will work as otherwise he poops on the kitchen floor and pees on one of the area rugs. Needless to say Neil isn't very happy with that!!

I have the litter boxes for the rest of the cats in the basement but he rarely goes into the basement.