Is my hoya dying?

The leaves are looking starting to look shrivelled and some are yellow and dropping off. I know hoya don't like being overwatered and prefer to be pot boundbut it has been pretty robust the past fifty years, (it was my MIL's) and I really don't want to lose it. I have cleaned the leaves with a summer oil solution, as I have done every year, since they get dusty and get a bit of black mould on them. It's in an outside porch, north facing.

Have you looked for scale or mites! These are common pests to hoyas. Maybe after fifty years the potting mix is mere dust.

I can't find anything, apart from the sooty deposits which I've cleaned off. I re-potted about 2 years ago.

Maybe try trimming some of the yellowing leaves. Have you pruned the vines before or since re-potting!

mine did the same thing and sadly she passed away after 20 years.

Mine is covered with blooms and smells divine. I only water when I remember which is not often and it only comes inside when it flowers as I love the smell.

Take a cutting from it in case it does curl it's toes up, then at least you'll still have a plant from the original.

It could well be either over or underwatering, without pic hard to say. Hoya are also prone to mealy bugs in the roots.

Thanks for your suggestions. I have a baby from the original, kuaka but the leaves also have the same withered appearance. I've never pruned the vines, I didn't know you should.

You don't need to prune them, unless they get too big. They sometimes get a rot around the roots which causes the plant to die slowly.
Check where the plant is in the soil. If the stems here are dead (usually the outer layer of the stem flakes off eventually) then it might be that. Cuttings from the stems will still grow though even if the roots are totally dead. They do like to be pot bound but don't like to stay that way especially if they are allowed to dry out for too long during summer. This causes some of the roots to die off and these can rot when it is re-watered. I'd look at the roots and check for mealy bugs as these are magnets for mealy bug. Repot the plant if you need to. It might just be too dry at the moment. They like lots and lots of water when it's warm. I have a longifolia at home which was getting shrivelled leaves just because it was drying out too much between watering. Came away again when i upped the water though.

I have one with green flowers and red centers in flower at the moment as well as buds on a couple of the "giant" ones. Even the best growers can lose large plants though, i keep back ups of everything i have room for. I've seen massive plants at the wintergardens in auckland slowly dying because the roots got rot. They will just take cuttings and throw the old one away.

Thanks for all that info deathrockboy. I'll get on to it first thing. I'm hopeful you could be on to something.