Q: Sparking Dipstick/Oil Tube

The vehicle is "probably" safe to drive but to give you a truly informative and intelligent answer, the vehicle would have to undergo a safety inspection which is not a bad idea in any event given that the car is 15 years old. Spark discharge, in the circumstance you are describing, has only two potential causes: 1) static discharge through your body to ground, via the metal dipstick; or 2) an electrical short circuit between a) the dipstick as it momentarily contacts a wire (or metallic part) that is connected to the hot side of the battery and b) ground, the engine block and dipstick tube being "ground". This latter circumstance, if it exists, would represent an electrical fault that should be identified and repaired. If you request the safety inspection, the mechanic will resolve this. Alternatively, you can request an electrical circuit/component diagnostic and the responding certified mechanic will resolve it that way. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.