Chao chi. Anh or ong???

[ratnew]

If you are a young lady (20-30) in southern Vietnam, how do you decide between saying anh or ong (for a close friend who is older than you) ?

1: If his age is more than ___?

2: How does your own age (help you decide) when you choose anh or ong?

3: How would your choice (of anh or ong) be changed by affection or respect?

(edited to be more clear about what I am asking)

[MANH NGUYEN]

Either one. But Vietnamese girls may be too shy for men to approach, so they like to use the word ONG.
1). No matter how old the guy is, the best choice is ONG, especially
when a girl meets a male stranger or a man at the first time.
2). Surely, it does. But a ten-year difference is fine, as long as you are not a homeless.
3). A gentleman with a good knowledge in general is always respected and welcomed ....Affection should follow....

[MANH NGUYEN]

Either one. But Vietnamese girls may be too shy for men to approach, so they like to use the word ONG.
1). No matter how old the guy is, the best choice is ONG, especially
when a girl meets a male stranger or a man at the first time.
2). Surely, it does. But a ten-year difference is fine, as long as you are not a homeless.
3). A gentleman with a good knowledge in general is always respected and welcomed ....Affection should follow....

What a puzzle is!
I need help, please.

[mhd]

1) If the guy is about my elder brother's age + 5, I would call him "anh". Other than that, I called "chú" or "bác" according to my father's age. I don't call anybody "ông", only when my parents called them "ông" too.

The other "ông" is used in business like meeting only or we don't know each other, like when two people talking on the phone. After we get introduced face to face, it would be "anh" or "chú, bác".

2) I don't go with my own age, I go with my brother's. Even as I get older, it's dangerous to call any older guy "anh", he would think that I like him the wrong way.

3) Yes, if I like someone enough, I would change "anh", disregarding to the first rule.

[ben.wills]

1) If the guy is about my elder brother's age + 5, I would call him "anh". Other than that, I called "chú" or "bác" according to my father's age. I don't call anybody "ông", only when my parents called them "ông" too.

The other "ông" is used in business like meeting only or we don't know each other, like when two people talking on the phone. After we get introduced face to face, it would be "anh" or "chú, bác".

2) I don't go with my own age, I go with my brother's. Even as I get older, it's dangerous to call any older guy "anh", he would think that I like him the wrong way.

3) Yes, if I like someone enough, I would change "anh", disregarding to the first rule.

I agree. "Ông" is not usually used by a lady to call another guy around her age or her parents' age for that matter. However, "ông" can be used in some special situations like between very close friends, the girl can call the guy "ông" and the guy calls her "bà" or in affectionate relationship/flirting situation.

Normally, "anh" is used if he's around your or your siblings' age (your generation), "chú" or "bác" is for older man who belong to your parents' generation, "ông" is normally for even older man who belong to your grandparents' generation.

[ncchinh]

Ông: is to address people who are 2 generations older than you. It also means "Sir" in formal situation.
So if that's a friend, and he is not too old (40-50 years older) than there is no reason to call him Ông. Vietnamese youths sometimes use "ông" to address male friends of the same age, but only in very informal and close situations.