DOT-4 brake fluid?

I’m changing my brake pads tomorrow and bought dot-4 brake fluid to refill the caliper. I compared dot-3 with dot-4 fluid and as far as I could tell, the only difference is the maximum temperature at which it protects. Dot-4 is a little higher. However, the owners manual says to only to use dot-3.

Is it okay to use dot-4?

Practically speaking, yes. The brake hydraulic system will work just fine with DOT4 fluid. The other significant difference between DOT3 and DOT4 is the rate at which they absorb moisture from the environment. DOT4 is more hygroscopic than DOT3, and will take in water faster. The effect of this is somewhat offset by its higher boiling point. It might be that a system filled with DOT4 should be flushed and refilled more often to minimize corrosion of internal components induced by moisture, though I’m not sure on this. The practical effect of just topping up the system is likely to be negligible, however.

Picky detail – you add the fluid to the reservoir on the master cylinder. Calipers are found at the wheels on disc brakes.

If you reset the caliper pistons without opening the caliper bleed screws, you probably won’t need to add fluid. It will be pushed up from the calipers back into the reservoir. Doing it this way is okay with non-ABS systems. If it’s an ABS brake system, you want to open the bleed screw on the caliper while pushing the piston back in (a hose from the bleed screw to a jar avoids a lot of mess). In that case, you will need to top up.

A site about brake fluid.

Doesn’t indicate that you can’t use it. The general rule of thumb is to follow the instructions in the owner’s manual.