Oregon allows open carry but also permits cities and counties to restrict carry of loaded firearms in public places. Oregon CHL holders are exempt from these city and county ordinances, but you won't be. You may openly carry unloaded anywhere. Unloaded in these places usually means also emptying magazines and speed loaders.
Places you can't carry loaded w/o an Oregon CHL that you will be near: Multnomah County, Portland, Oregon City, Tigard and Beaverton. There are other cities on the list, but those are the ones in the Portland area. Be aware that you also can't carry in a public building without a CHL (hospital, courthouse, library, etc).
Right now in Oregon case law says that your car is a public place so the above carry restrictions are not lifted because of being in your car where the public has no right to enter. Thank a Multnomah judge for that brilliant ruling.
If you are in a public building you must allow an officer to inspect your firearm to see if it is loaded or they can arrest you. If loaded you must produce a valid CHL or be arrested. If caught on the streets of Portland open carrying they have no way to prove you are violating the ordinance unless you commit a crime, that is how unenforceable the loaded firearm ordinances are, thanks to the 4th amendment.