I had a situation with my dogs come up that has led me to ask the retriever community this question.
Several weeks back I was at my cabin with my two chessies, a ten year old male and a 6 month old male. On one particular morning while doing my morning routine I could hear one of the dogs vigorously drinking and thought nothing of it until it continued for several minutes. Upon investigation, I found my little guy Link helping himself to the prior nights fryer oil that was left outside. I yelled at Link from a distance but all that did was make him drink faster. By the time I got to him he probably drank over a quart of oil. The oil consisted of vegetable, sunflower and peanut oil. I monitored him for the next 24 hours and all seemed to be okay except for the pure oil at the end of his stool. I soon forgot about the oil incident until the following day when I took both the dogs swimming with a few friends. After two people came up to me to ask why Links coat does not get wet it finally dawned on me that the oil may of had something to do with it. Now I am not talking two degrees of wet. What I and several others observed was one dog with a completely saturated coat and another with absolutely no signs of any moisture being held in his fur. I mean his coat was completely dry coming out of the water.
So this had led me to think that there may be some benefits to adding oil to my dogs diet for cases of extreme weather or extreme cold water work. I dont think I would do this routinely, but when the weather turns cold and we start breaking ice, this may help my dogs endure the harsh conditions with less of a fear of hypothermia and etc.
I would be interested to know what others think and I also thought I heard or read that sunflower oil may be toxic to dogs but have never found anything on the subject. It also seems like Link consumed an awful lot of oil and I am not sure if such a mass consumption is good for them either. If there is some substance here, it would be interesting to know if certain oils are better than others and also a recommended quantity and frequency.
One of my friends tried to tell me he used Crisco topically applied to his dogs coat but all it did was make the dog shrink. I guess that's why they call it shortening!