Here are my tips:
Securing the save of vehicles: DO NOT wait until the 1 minute restart warning to park your car and sync data, car saving does work and it is reliable however you need to give the server enough time to detect where the car was last parked, if you park it in a safe spot at the 5 min mark and wait out till restart your car will save
Locked vehicle after restart:
This is a minor bug, after restart you cannot unlock your vehicle until like 20 seconds after you entered the server. Just keep spamming U until it unlocks
Missing Y inventory items:
This glitch is tricky, I personally don't know how to replicate it but the what I've come to conclude is that if you keep your inventory weight under 64 your chances of keeping your inventory are something like 90%, also beware there is a glitch when running oil, each oil is suppose to weigh 1, however when you do process oil barrel the weight of each oil decreases I've had times when I have about 100 oil on me + rubber and my weight is in the 70's, this is a glitch and in reality your weight is over 96 which is the max weight with the big backpack. Being over max weight will cause you to loose alot if not all your items in your inventory during a relog or restart. To fix the weight issue you simply need to put the oil in a crate or vehicle inventory and pull it back out, it shall then display the correct weight.