Hi Tweedle,
The parts are mostly indicated in the MatthewsVolvoSite.
I contacted a local hydraulics company and explained what I needed.
I think I got a few metres of Multi-Oil hose from this company. Just a few pounds AFAIK.
https://www.hydroscand.co.uk/uk_en/p...oil-and-petrol
Find out what the maximum oil pressure might be in your engine. I would think this forum could help you. Maybe look for oil cooler posts.
Tell the local company what you are using the hose for, provide photos or (measure length first and mark the fittings so that you reinstall in the same orientation and then cut the old hoses off) or take the existing fittings in with you if you can, show them the old hose etc, and agree on the desired internal diameter of the new hose. Get appropriate clamps (they will make a recommendation). I used 2 simple crimp clamps per each connection (pence each - I bought a few extra). I staggered the crimps.
I was working with ATF which I believe is fairly low pressure, but I'll leave it to you to find out max engine oil pressure. I think oil pressures are not very high compared with what hydraulic companies are used to dealing with so you shouldn't have a problem.
Once you have done the one that is leaking, I would be tempted to do the other so buy extra hose.
BTW of those two Volvo hoses the out and return are different prices and are available aftermarket.
But DIY is the cheap and satisfying option.
I used a Dremel with a EZ SpeedClic SC456B Metal Cutting Wheel to cut the fittings, it's a really good tool.
HTH
Steve