SELECTING AUTOMOTIVE WIRE
in doubt, use 125°C rated TXL, GXL, SXL, or SGX wire insulation for engine
compartment and general wiring. The only difference between these
is the thickness of the insulation and cost, with the thicker being the
more expensive. They are all insulated with crosslinked
polyethylene, which is almost as heat resistant as teflon,
cheaper and much tougher.
NOTE: SAE J1128 GPT is a PVC insulated wire rated at 85°C used for general chassis wiring, and should not be
used in the engine compartment of your car according to the SAE J1128 spec. It's not as tough or heat resistant as
TXL or GXL insulation, but it is considerably cheaper. This is the wire found in retail stores.
For more info on TXL, GXL, or SXL/SGX Wire,