Firstly, you have done pretty well with pics - even knowing what is needed & being experienced, I know it's often hard to get good ones. Of the feet on the ground, you need to take them more squarely from the side & front, and from at/near ground level, as angled like that gives a skewed view. But they're good enough to get/give a reasonable idea I think.
First comments on what you have written, then on what I see...
I know his hooves are dry, I'm putting hoof oil on him as often as I can.
Of course, as with everything, don't just take my word for it, but look into the subject thoroughly yourself...
Hooves are MEANT to be dry on the outside! Assuming they're healthy, the outer layer is impervious anyway, it doesn't absorb any moisture, but keeps what's inside, inside. And oil is not 'moisture' as such anyway, like water. When there are breaks - cracks, chips etc - extra moisture can get in, as can fungal & bacterial infections, and to keep it moist, or seal it in with oil, blocking oxygen & it's ability to dry out, tends only to make for a better environment for the bugs to thrive, and make horn soft & weak, more prone to further infection too. Therefore I'd strongly suggest you ditch the hoof oil, and instead encourage the feet to become dry.
If hooves appear to look 'too dry', shelly, flakey, etc, then the likelihood is that nutrition is a big factor, and that too *wet* environment may also be. I don't see anything here anyway that give any appearance of 'too dry' - quite the opposite actually - but with 'micro cracks' as can be seen here, that is very often nutritional too.
Anyways, from what I can see they look contracted and underrun (maybe??)
Absolutely! As a 'new to the horse world' person, you have obviously learned & observed more than many much more experienced! It's a big subject, not to mention there is so much else that's important for you to learn, so don't ever feel bad for not knowing better - just strive to keep learning!
Now, firstly another 'disclaimer' about not taking my word for anything blindly. Not least because even the best pics & a little info on a forum cannot give a full & completely accurate picture. Therefore, take my comments as 'food for thought' and the illustrations only as a *rough* idea.
And BTW, I'm well aware, that with eyes accustomed to evaluating in order to rehab, that I can often paint a too scary picture, by picking every fault:eek_color:, especially if you know little. But I keep doing this, because I want people to recognise & understand/consider all the factors that I am mentioning. It doesn't mean your horse's feet are going to fall off! ;-) They actually don't look that bad in most respects, FYI. So, having said that, lets get down to nitty gritty...
In the first & 3rd pic, you can see heels are 'run forward', as are toes stretched forward. I have drawn on the 3rd pics to further illustrate; red lines = problems, green lines indicate *approx* where the hoof 'should' be. As you can see in the red lines following the toe wall, the lower ones deviate from the hoof - that's to show how much further forward they would be, but that the farrier has removed some of the flare from the outside - that's not in the least necessarily wrong, just pointing it out.
It's good to see the farrier has obviously recognised the toes are stretched and applied 'Natural Balance' type shoes set back and with a bevelled 'breakover', which may well put the toe/breakover at a good spot. Please study
Home to get a better idea of the whys & wherefores of that.
I've also noted the hairline on the left fore at least, looks a bit... dippy(I did exaggerate the line a bit to make obvious). Indicating already a bit too steep an angle & extra pressure on the toe walls & hence hairline. Adding to that, you will see by the green heel lines, I've marked the left fore heels as already 'too high'.
**He may 'need' to be be higher in that foot though - horses, like us, are often not completely symmetrical, and there is often body imbalance that means to 'correct' the foot to 'ideal' heel height may cause body issues/discomfort to worsen. So... I would want a hoofcare practitioner AND a good bodyworker working together to ascertain whether/how much it should be 'corrected'. Or not. Look up 'high-low syndrome' or 'clubbed foot' to learn more.
The Barefoot Blacksmith ? Healthy hooves for life-long soundness have some good info on that, on their articles page.
The sort of 'ledgy' or 'ski jump' look to just above the hairline of the left fore is a *possible* indication that the hoof wall has been pushed up higher in relation to the bony column(or conversely thought of as the bones 'sinking' within the capsule). **IF this is the case, it doesn't look terrible & is actually a very common issue, especially for horses shod with peripheral rims. May want for extra support under the front of the foot(sole, NOT walls) too.
Unfortunately, applying rim shoes, especially inflexible, especially without appropriate support *under the frog* is contraindicative to fixing/improving run forward or weak heels. Not only does the foot need to be trimmed well & in such a way to minimise excess pressure on the already crushed heel walls, but the frog & what is above it needs *comfortable* stimulation & support. I'd be therefore using 'frog support wedges', under the frogs, NOT under the walls, and holding them in/on with either hoof boots, or flexible shoes which also protect and support the heels, frog, soles, such as Easyshoes or Eponas or such. *Given the wall breakage & likely infection needing to be cleaned out at the quarters though, I'd be inclined to boot rather than shoe, at least until that's all good tho.
Hind feet - as per info on lamenessprevention.org, blue lines indicate *approximate hoof balance & where 'breakover' should be. Tho that's VERY rough, without considering all relevant points, being from that pic only. Seems toes are also a tad stretched from this. Looks like heels, while a bit run forward, may well be too low in the hinds - I find the lack of definition of bars & lumpy look to soles just in front of bars also goes along with that. It is unclear at all, from that pic, just how deep the toe is in relation to the heel though. Pink on toe sole is bruising tho, and as heels, while not so contracted, are weak, I would want to protect/support those feet too.