I've had OSB in our garage since we built our home twelve years ago. Untreated, it seems to still be in pretty good condition. I'm putting the same material in my shop in the next week or so.

I treated a new flatbed trailer with boiled linseed oil a few years ago and think it did a great job for a trailer. Being in the weather I think I will retreat it again very soon.

Have any of you put this stuff on shop or garage walls? The only other material I've thought about is water based polyurethane. What do you think?

Water based poly, floor poly is very tough and dries quick. I use it on my mantles and tables/desks I build.

Why not primer and paint?
I have a 10x24 feed/tack room that has held up well after almost 20 years primered and painted, plus it doesn’t look like OSB. lol

I'd go with poly, IMO it looks good just sealed. Linseed oil may stay sticky if drying indoors.

I skim coat OSB with joint compound and sometimes even texture it it looks like sheetrock first you have to prime it with a water-based primer or the wet mud can cause it to swell.

The OSB installation job on the shop is any day now and it will be the perfect time to treat it. The garage is another issue, plenty of emptying out first. Poly is sounding like the best idea for the shop because appearance doesn't matter. If my wife wants to help empty out the garage, and if she wants to help paint it, then we might go that route on it.

that's a big plus

As for your trailer I've had good luck with 1 gal.used motor oil and 1 gal of diesel. Mix together and apply with a small pump up sprayer. Cheap & EZ.

Does this leave residue or stay slick?

If it’s osb, I’d prime and paint. Especially if it’s the slick side.

It soaks into the wood and not slick or residue is left. Since I sprayed mine on after it soaked in (day or two) I shot the metal trailer frame with some engine degreaser and hosed it off.