TXL & GXL 125°C Rated Wire
This wire is rated under SAE J1128 for temperature up to +125°C or 257°F. For general circuit wiring.
Recommended by the SAE for underhood use.
SAE J1128 Wire Insulation Types:
TXL, Light Insulation Thickness, 18 to 12 ga. wire
GXL, Medium Insulation Thickness, 18 to 12 ga. wire
SXL, Heavy Insulation, 8 and 10 ga. wire
SGX, Heavy Insulation, 6 gau. to 1/0 ga. wire
This a much tougher and more temperature resistant wire that the 85° and 105° wires, and is generally not available from retail auto supply stores. This wire is insulated with crosslinked polyethylene, (XLPE) which is what gives it the 125° C. temperature rating.
It is a much better insulation than the polyvinyl Chloride (PVC ) wire sold in your local retail stores. XLPE has a higher temperature rating and a much better solvent resistance, and is mechanically much tougher.
It is what the automakers use when they manufacture your car or motorcycle. The cost is generally only about 20% more than the cost of the other wires, which makes it a real bargain.
For more information, see the WireTables