1992 Oldsmobile "98" starting issue

My mechanic is stumped about my oldsmobile starting issue. He has replaced the starter, but that apparently was not the problem. It seems when I start the car and drive somewhere and then turn it off, do whatever and then try to restart the car, it won’t start back up. Sometimes I’ve had to wait 20 to 30 minutes before it starts, or once I just left it overnight in Wal-Mart’s parking lot as it wouldn’t start up again. Other times you can run several errands, starting/stopping/starting again like normal. You never know when it will happen. I no longer will drive it out of town for fear it will happen there and maybe not restart. It has become the car that you never turn off! I use it just to run round trip errands without turning it off. Does anyone have any suggestions about why this happens and what can be done to remedy it? It is sort of like being sick and going to the doctor, but as soon as you get to the doctor everything is fine. When I take it to my mechanic it never happens to him! Any help or advice would be greatly appreciated! Thanks.

What happens when you turn the key? Does the starter work, spinning the engine, but the engine doesn’t start, or does NOTHING happen? Do you get any noise at all?

We need more detail.

Sorry about that! When I turn the key in the ignition, all the lights come on but no sound. No click, no noise. Just lights. Starter does not work, nor does the engine spin or start. Nothing. Eventually, when you lest expect it, you turn the key in the ignition and it starts the car up. But you never know how many times you will have to try to start it before it actually starts up. Does that help?

I am assuming this car has an automatic transmission. The next time this happens shift the transmission to neutral (use the service brake to hold the car from moving) and see if it will start then. Also if you like, run the transmission selector down into drive and back into park and see if that helps the engine crank. You may have a problem with the neutral safety switch.

If this Olds has a manual transmission, cycle the clutch pedal; hold the pedal to the floor; and see if you now can get a crank.

Hope that helps.

Thanks for the advice…I will try that. Just curious tho, do you know WHY my car does what it does? I would like to tell my mechanic so he could fix whatever the problem is. Thanks for you help.