typically won't hurt it, don't make it a habit and change the oil asap
Yes you can mix different brands but I recommend you do not mix different weights. You can even mix synthetic oil with conventional oil. But as the weight of the oil is critical, do not ever mix one weight of oil with another, no matter if it is synthetic or conventional oil.
Yes
20w50 motorcycle oil, any brand.
Of course you can but when you do you are changing the viscosity of the oil. Your engine requires a certain weight or viscosity of oil. Use only the weight oil recommended by the manufacture.
You do not mix gas and oil in a kawasaki kz 400 motorcycle.
There is no specific weight regarding Motorcycles. There are two types of Motorcycle weight.The dry weight of a motorcycle excludes some or all of the following: gasoline (or other fuel), engine oil, coolant, brake fluid, or battery.The wet weight of a motorcycle includes, but is not limited to fuel, engine oil, coolant, brake fluid, and battery.
Any motorcycle oil with the weight 20W50. I use Valvoline 4 stroke motorcycle oil 20W50 and it works fine!
Oil fuel mix ratio is different for different engines, please contact the manufacturer Fuel air mixture is the same @ 17 to 1 by weight.
20/50
10w40 Motorcycle oil
yes you can mix oil brands. it is not recommended to do though. As long as the weight of the oil is the same.
One can find reviews for motorcycle oil in several different places. One can find reviews for motorcycle oil at places that sell motorcycle oil, like Amazon, Mobil Oil, and Advance Auto Parts.