I have a Johnson 115 year 2000. It's relatively new to me and I've just put in a gallon oil since the oil that was in there when I bought it has now run down. The question is....should I be putting any special 2 cycle oil in (perhaps Johnson brand or a specific brand), or will the West Marine TW-2 house brand gallon jug be ok (which is what I just bought a few gallons of and used this time). Thx, sd