Thanks! I got some Valvoline synthetic since it said it's compatible with DOT3 and 4, and I plan on flushing my brake system soon as well, so I'll use it there, too.normore said:DOT 3 or 4 will be OK. They are compatible and mix together fine. DOT 4 has a higher boil point (not needed for clutch) than DOT 3 but also has a higher moisture absorbancy rate. Valvoline synthetic is designated as DOT 5.1 fluid and is compatible with DOT 3 and DOT 4. DOT 5 is incompatible with all of the above. It is a silicone fluid and is not recommended for any application on the Supra .