The reason for adding the TCW-3 oil to the diesel is to increase the lubricity of modern ultra-low sulfur fuel to reduce pump wear and such. Do you have the ultra-low sulfur fuel where you are? If not, you can probably skip the TW-3 oil and be fine. As for which brand of oil to add, I doubt if it will make much difference. Personally, I would use 5 ml per liter of the cheap stuff if I was going to add 2-cycle oil.