#1 is closer to kerosene, #2 is standard diesel. Winter blend diesel is a mix of #1 and #2. #2 diesel has higher BTU's, and is typically the fuel that you run during the summer months. #1 diesel has a lower energy content (BTU's) and also less lubricity. This causes a loss of power and a drop in mileage. The reason #1 diesel is blended with #2 during the winter is because of the gel point. #2 diesel will cloud or gel quicker than #1 diesel. In cold weather, you don't want your fuel to wax up or you'll never get your truck started. By adding #1 to the mix, your fuel won't gel up (unless you're in Alaska or something).
Bio is always indicated by the letter "B" followed by a number, and is rated as these examples:
- B2 (meaning 2% bio diesel, 98% diesel)
- B20 (meaning 20% bio diesel, 80% diesel)
- B100 (100% bio diesel, no regular diesel added to the mix)
Bio can be any blend and range from B2 to B100 and anything in between. Just B2 alone gives more lubricity than any fuel additive you can buy.