This is a multi part vote meaning you can vote for more than one.
So please vote if you use synthetic oil or Regular Dino Oil in your car or truck and at which mileage?
Of course comments are fun & appreciated~)

Regular and 3000. Even though I use oil that'* rated for 5000, I like to be safe and ensure the motor is going to run smoothly for a long time to come

I do the dipstick test. If the tip feels slimy and slippery, the oil is still good.

Synthetic Oil for me, and I like to change it every 3-4k miles.
In my case it takes me longer than most to reach 3-4k, so I'll check the color and viscosity, and change it if I feel it is necessary.

Castrol Gtx part synthetic for high mileage engine is what I use. Gets changed every 5-6k Miles.

i buy long life 9k oil. so i change it every 9k. have to add a quart at about 8k or so. i think thats pretty good for an engine with 180k on it!

I use Mobil 1 and change it every 3000.

I use Mobil1 or Castrol synthetics mainly. I have been experiment a bit lately with semi-syns or high mileage flavors too.
I do find on the long hwy trips that I do get better fuel mileage with full syn oils by about 1-2 mpg better than semi-syns.
I normally do oil/filter changes in the 3-4 k range, as oil is brown at bottom of dipstick overnight by then, and not as slippery anymore.

Regular dino and 3,000 miles. I know the oil hasn't broken down by that point and is probably good for more miles, but I just like the idea of flushing the engine out. Plus, it gives me a reason to get under my vehicles on a regular basis and check things out.

No offence to those who do, but I don't understand why you would use synthetic and change at 3,000 miles.

I agree. I changed at 5k when I used syn. Just not worth it at the moment for me to use syn (engine is going to need rebuilt within 50k max anyways)