No, I wouldn't use Ironrite Gear Oil
Even if a NOS can of the stuff could be found. It easily would be >50 years old and why go through all the bother of an oil change just to use something that could have broken down from sitting on shelf.
Ironrite merely sourced lightweight gear oil (SAE50)from Gulf oil, and repackaged in their own cans. As a substitute any SAE50 gear oil (non detergent) will do fine.
http://www.jitterbuzz.com/the_ironrite.html#oil
The portable fold down Ironrites like my B890 obviously didn't use gear oil (it would leak out), but simply greased the gears with white lithium grease (Lubriplate).
The owner's manual gives great directions on replacing the roll pad cover and taking care of pad.
As with nearly all domestic ironers the roll padding is made from knitted cotton, and cannot be found today for love nor money. So take care of yours! *LOL*
Well you *can* find knitted cotton padding for ironers, but it is sold by commercial laundry supply houses in widths for industrial ironers. The fabric can only be cut by a very powerful and well built serger/overlock machine. Unless edges are over locked they will unravel.
Keep your eyes on eBay, CL, thrifts and so forth. NOS padding and roll covers pop up often enough. It never hurts to have extras on hand.
Read somewhere that it is possible to get away from all that oil chaning with old Ironrites by simply using white lithium grease instead. This means of course draining the old oil first, then cleaning out the gear box (with some sort of solvent I shouldn't wonder), before greasing them up with Lubriplate. On the upside once done the thing would be "permanently" lubricated or at least for a *very* long time.
Cannot stress enough regardless of what method or product used, after lubricating an Ironrite make sure the area around gear box is totally clean. There isn't much room back there and freshly laundered and ironed things can easily be ruined by coming into contact with oil/grease.