i'd say its better. you might get leaks, because regular oil has bigger molecules than symthetic. i run synthetic in my truck with 193,000 miles all the time no trouble
synthetic to conventional - ok conventional to synthetic - no
Yes, you can even mix them.
Yes, you can even mix them.
Earth's poles are to switch every few hundred thousand years.
yes
No, you can even mix synthetic with conventional oil. It will do no harm at all.
No it is fine to switch back to regular oil.
yes, if the car manufacturer dictates that regular oil is acceptable. If your car requires synthetic oil as dictated by your owner's manual, then DO NOT use regular oil. May void warranties if your car is still covered.
If you have kept regular oil changes, no prep is required. Just go and put the synthetic oil in.
yes it is fine but of course synthetic is the best to use if you can. Double check your oil requirements with your owner's manual. If it states that normal oil is okay, then go ahead. If your owner's manual dictates Synthetics, then DO NOT switch.
It is 1.4 thousands
Yes, you can not only switch you can mix synthetic with conventional oil.