-- Last Updated: Nov-07-12 3:00 AM EST --
For those who are unfamiliar with Deks Olje, Deks D1 is the basic penetrating oil. Deks D2 is applied after application of D1 if you desire a satin or high gloss finish.
To get the best results, the Deks must be applied according to instructions. D1 is applied to the wood in repeated coats, about every 15 minutes or so, until the wood will not take any more. This will typically be 5-6 coats. If D2 is not applied after D1 the finish will be matte (but quite pleasant).
If you want a satin finish you can apply a couple of coats of a 50:50 mixture of D1 and D2. If you want a high gloss finish, multiple coats of D2 are applied.
The main difference between the handling of Watco and Deks is how the oil penetrates the wood. Deks seems to penetrate better. Of course, you can try to emulate the Deks D1 application process with Watco, but after about the 3rd coat, Watco just sits on the surface of the wood and turns gummy, unlike the Deks.
So the Deks application process is more time consuming and Deks is considerably more expensive. But in my experience it produces a much nicer luster and is way more durable than Watco oils.
I have known people who have gotten cosmetic results with Watco oils nearly equal to that of Deks, but they applied Watco oil after every trip out. So maybe if you are willing to apply it dozens of times a year, Watco will eventually penetrate wood to the same extent Deks does.