We all have one or more Philips head screw drivers in our tool boxes. It's pretty much impossible to be a DIY'er without them. But, if you own an a vehicle that was manufactured of Asian origin, chances are, the screws on it are not "standard" Phillips head. So, if you find that your Phillips head screw drivers are ruining your fasteners, it very will might be because you're using the wrong tool for the job.
Lesser known is the Japanese Industrial Standard (AKA JIS). Bottom-line, a standard Phillips driver will not go into a JIS screw all the way because the corner radius of the screw is smaller than that of a standard Phillips driver. Because of this, it leads to what is referred to as "cam-out". In fact, the standard Phillips was created to allow this, so that you know when max torque has been reached, avoiding over tightening or worse, snapping fasteners.
The differences between Phillips and JIS are not easily seen, so this illustration should help.
Sometimes screws will be identified as being JIS if there is a dimple or dot on its head. But, this isn't always the case. But chances are, if you're working on a Japanese machine, the Philips head screws will be JIS.
JIS screw drivers are not hard to find, ranging in price from the mid to high $20.00 for the budget stuff, on up to 3x (or more) that for the good stuff. Good tools, if taken care of can last a lifetime and the right tool for the job saves time and money in the long run. We run Vessel brand JIS in the TT shop and they are probably the best screw drivers we've used.
Edited by Bryan Bosch