The dot 3&4 refers to boiling point of the b/fluid.I wouldnt recommend putting dot 4 in the new landcruisers with ABS weve had a few in abs m/cylinders (aprox $1500ea) in under warrenty for not operating correctly. Low brake fluid indicates 2 either 2 things 1/a leak or 2/ low brake pads and/or shoes checkem,- dont fill end forget.