DOT 3 and DOT 4 are glycol ether based. You can mix DOT 4 with DOT 3 brake fluid, but never add DOT 3 to DOT 4. DOT 5 brake fluid is silicon based and incompatible with any other DOT brake fluid. DOT ...

To date, Toyota is aware of 12 warranty claims and 5 field reports that relate ... the segment's best-selling midsizer takes either DOT 3 or DOT 4 brake fluid. To be sure which one is right ...