The difference between 20X and 30X is that 20X is the Super Long Life Blue while the 30X is the more conventional green coolant.
While you can use either, the blue coolant (20X) is better and also what the Kizashi comes with from the factory.
The good news is that you don't need to use Suzuki's formula. All the blue coolants are pretty much the same and that's why you heard you can use Subaru's Super Blue. The Japanese manufacturers pretty much use the same formula for the coolant.
You can even get aftermarket coolant. I got my Super Blue at Autozone. It's made by Pentosin but the coolant was made in Japan.
I actually posted about this in detail in the link below. I also called American Suzuki Motor Corp to verify that I can use any Super Blue. They are the ones who told me it's all the same stuff and there's nothing special about Suzuki's coolant vs. another Japanese Super Blue coolant.
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