The oil pan does not have a gasket, just glue. So you cannot lower just part of it. The subframe stays, but you will need to push some of the hard lines out of the way - Volvo did not want to make things easy.

Beware, not all of the oil pan bolts are the same size! So, when you take them off, arange them so they go back in the same holes.

Best to order new O rings and put them on while the pan is off. Also, the pan and block must be spottlessly clean before putting on a new coat of glue. Volvo RTV is expensive, but if the pan ever has to come off again you do not want to use off the shelf RTV glue.

This is not a simple task! Have you checked the pressure sensor yet? I would take it to a mechanic I trust and get a second opinion.

Klaus
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Always willing to listen, just not able to take direction.