If you have a W123 then that is common, almost normal. {with
any refrigerant}
Same pretty much for pre-'93 W124's too I believe. Especially if converted to R134a. {since I was able to read your mind}
Put your car in your signature or in the body of your question. It is a pain to have to go look at your profile to find the info, and annoys those above who are most likely to have your information.