Why is my border terriers fur greasy?

Terriers sometimes will do this and what I find to do is get "GOOP" you find it in the automotive section at your local Target, Walmart any place that allows you to purchase auto supplies. Rub a quarter size amount into his coat where it is greasy if it is all over then use a little more and rub into coat well then bathe with Baby shampoo not puppy Baby shampoo the yellow stuff that you can get from Johnson and Johnson or any other baby shampoo company. This has worked for my for many years. I am a groomer and have groomed alot of breeds with greasy coats and this is the best remedy I have found it works on cats too.