KR-
An undercoat on a dog is actually a very short, second coat on your dog. It is insulation for your dog in colder temps. Undercoat is usually so short on Sch. that you can only see it if you card or Furminate them. That's when it pulls the dead hairs in the undercoat out. It's really important to remove the dead undercoat every so often. If you don't, then air won't get to the skin, and your dog will start to develop skin probs. Your dog has one, I promise
Brandi-
A coat "king" or coat rake (same thing) is gonna be your best friend. Start by brushing your dog with a dog brush. Then, begin to rake the coat with the coat king. Do this until no more hair comes out. This pulls the undercoat out. The undercoat is what your dog is losing right now. It's causing your shedding. You keep raking until you can take a wide tooth comb through your dog's coat with minimal pulling. Do this about once a week. Brush every other day in between. You should consider taking your baby to a groomer that can use a force dryer. It helps to blow some of that extra coat. Once you get the initial bunch of hair out, it will make your life easier.
As for the hot oil treatment? We don't do this, so I am not sure what it would be good for. Dogs don't tend to get dry, frizzy hair. They tend to be oily and actually need degreaser. I would have to ask them what they use it for. My mother is a NDGAA Certified Master Groomer. I am studying for my certification right now. And, we don't use anything like this in any of our three shops. Go to the NDGAA website. You should be able to find a certified groomer in your area. I know you can call them and they can tell you of one near you. Only go with Certified Master Groomers. If someone says they are certified, ask with whom. Petsmart "certifies" groomers. It's not a good situation, b/c they are not properly trained. But, it happens.
Madmax- Bearded Collie? No. But, it would be much like other breeds. Brush, brush, brush. Get a very wide tooth comb. Brush until you think you've gotten all matts and tangles out. Coat king/rake his coat like I told Brandi above. Then, run a comb to find any spots you've missed.
It's very important to check the underarm area for matts. they tend to collect there. Also, check the hair in between the dog's pads on the underside of the paws. Literally put your finger in between the pads. (It won't hurt them.) Check to see if the hair has become matted. If so, you may need to take it to a groomer or vet so they can shave it out.
But, the most important thing is just to prevent matts from forming by brushing and removing the undercoat. It is responsible for almost all matting.