Not odd at all. My preferred clutch and brake fluid is Castrol which also is DOT 3 and DOT 4 compatible. You can use DOT 4 in a DOT 3 system. But you shouldn't use DOT 3 in a DOT 4 only system.

In case you did not know, you can not mix DOT 5 with anything else.

To use DOT 5 you have to completely clean and I mean completely clean the entire system of any of the residual lower grade fluid. And this requires removing, disassmebling and cleaning y of the calipers, wheel cylinders and proportioning valve if equipped and cleaning the hard and flex lines thoroughly.

I don't recommend using anything but Castrol brake fluid in either the brake or the clutch systems.

But I know others feel differently and they think DOT 5 is best. But I think DOT 5 should only be used in race cars and in high humidity areas.

Good ole Walrus (George Downs)used to regale us with stories of the time he spent down in Panama and the problems he experienced with the high humidity and the saving graces of fully synthetic non-hygroscopic brake fluid before he passed.

Walrus, you are still missed!