Not all wiring is created equal.
Going over the link Hutch sent out for striped wire- Just a word on buying new wire. Three types of underhood wiring are available. TXL, GXL, and SXL, with the XL signifying "cross-linked". This means the sleeving is PVC, but is pressure extruded to adjust molecular arrangement making it more resistant to heat/abrasion. Try to get GXL for underhood stuff or wiring that could see higher heat or elements. It's got a bit thicker sleeving on it than the TXL, which has the thinnest sleeving. A step up from GXL is SXL, but it may or may not fit into tight connectors. So, just keep that in the back of your head. But if it will fit, SXL is the best choice IMO, followed by GXL. All three types are good for underhood applications and are pretty good at withstanding abrasion, moisture, oil, grease and most acids. Rated at 60V with -60 deg F to 257 deg F temperature range.
GPT is general purpose thermoplastic wiring, and suitable for many inside the body and door wire applications, but it's furthest down the food chain. Ratings are 60 V with -49 deg F to 185 deg F temperature range.