6mm
The size of the screw needed to mount a license plate on a 1998 Cadillac STS is 1/4-inch?æby 1/2-inch. They make license plate kits that includes all needed hardware.
1/4" x 20 threads. 1" long.
Use metric 6 mm or 1/4 inch self tapping screw to attach plate. ( North America only )
theres no point in putting this question on wiki answers just ask the person at the garage
License Plate Light Bulb Size: 6418
Varies by manufacturer.
M6x1.00x20mm
4.2/16 Metric
I think 5mm X 20mm.
based on another thread, this is the info i found. These are the parts indicated on EPC. However, I went to the dealer with these part #s and they are just for the front license plate. Part # 0019904236 (5x12) is somewhat of a sheet metal screw which you need since the front license bracket is a hard plastic material and the holes on there need to be threaded by a sheet metal screw so the license plate itself can be screwed securely onto the bracket. This screw is perfect length if you are mounting your front license plate without a license plate frame. As for part# 0019846429 (5x16) this is a longer screw for mounting the front license bracket to the bumper. Don't need to worry about this one. The license plate screws for the rear are completely different as there is a metal mounting plate adapter that already has pre-threaded holes. You need metric screws M6 1.0 (1.0 is the thread type). Default length is 16mm but you need 10mm if you wish to mount your rear license plate without a license frame otherwise the longer length will drill marks into the rear lid and with a gap between the plate and the screws. I can't find the M6 with 10mm length at my local hardware store. I will need to stick with the ones that came with our car M6 16mm (part# 007985006197) but will need a license frame on it for it to work. I know there's not too much on this matter and no one really cares too much if the screws on your car already work. However, dealers just slap on whatever screws they have on their service bin upon delivery and no one knows what screws you really need for the car. This explains why some folks here complain about loose license plates. Anyhow I have attached both the front (left) and rear screws (right).
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