[SkyDog]

should I put also use DOT 5 brake fluid?

Do not put DOT 5 fluid in your car.

DOT 5 fluid is silicone-based, and is chemically incompatible with the glycol-based DOT 3 & 4 fluids listed in the car’s owners manual.

The practical differences between DOT 3 and 4 are boiling point and water absorption. DOT 4 has a higher boiling point, enabling it to handle higher brake temps better. But it can also be more water-absorbent, necessitating more frequent brake fluid changes.

There’s also DOT 5.1 brake fluid, which is glycol-based and compatible with 3 & 4. I don’t know offhand if there’s a reason it’s not approved for the BRZ/GR86.