Castrol 12509 Brake Fluid DOT4


This is a decent fluid with a low, low price. DOT4 classification means that this product brings a high boiling point. Its other main selling point is that it has been designed to mix well with other fluids – either DOT3 or DOT4.

In that sense given the low price but also relatively small bottle size of just 12 ounces, this could be a great top up fluid. Keep it on hand and apply it when a braking system is starting to feel spongy or you’ve partially flushed the system.

Of course the low price for the 12-ounce bottle means you can also pick up a few at a time for complete system overhaul.