Find a Crescent/Adjustable wrench that opens up that much and see if it will fit in the space available; use it carefully.

It is not the wrench that is the problem. I would read up on the stripping threads issue on the Oil Cooler.

On a 123 you will also need a thinned 7/8 or I think it is 22mm and a something to hold the fittings on the Oil Filter housing that are 24mm. I think that wrench would also be best thinned.

I used a big 1-1/16 Crows Foot I bought on eBay on a 1/2 inch drive Breaker Bar.

If you are in a big city find the cheapie tool store that sells made in China tools.

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84 300D, 82 Volvo 244Gl Diesel