I've offered this problem to your combined wisdom before. My 87 syncro TDI runs oil temps higher than I'd like: 240-250-260 just going down the freeway, level road outside temps from 50-80 or higher really.
Many possible solutions were offered, anything that hadn't been done was tried. No joy.
there were a couple of people that said they'd had the same problem and decided to just ignore the oil temp as long as the coolant temp didn't get too high.
That's the final option so I'm trying it but with a twist. I thought summer is coming now's the time to get the a/c hooked up and working. After all what's a little additional heat load, right? Given the quirky oil temps maybe it'll lower them!

If this all comes about I'll let you all know what happens - probably from the side of the road.
Mike