Thank you Lonewolf for bringing this to attention and doing the hard work, it is indeed the same on PS.

Upon arriving to a stash and parking my car before the restart (letting the restart be what kicks me off the server) and rejoining once the server is back up the Radiator and Fuel Tank has the same amount of fluid that I left in it.

However, leaving the area before restart (I ran atleast 1km) and then coming back right after restart drained my car of all fluids.

Im going to be testing the time limit next, I will log off 15 minutes before restart and then log on 15 minutes after, I will set my timer for 31 minutes, my test is to see if the fluid drains based on time and not just restart to restart based player rendering. Im pretty limited on how far I can test things but Ill keep updating this post if anything changes on my end.

For reference this is all on an Offical server on Chernarus.