There are many dialects in Igboland. Hardly do two different communities in Igboland speak same dialect. The situation is not different in Nnewi. With many towns bordering Nnewi,the people of Nnewi maintains a very distinct dialect.
With civilization,travel and education,the Igbo Izugbe (Universal Igbo) has watered down,to good extent, the very distinctiveness of Nnewi dialect but still,an average Anambrarian can identify an Nnewian by their few remaining dialects.
I will interprete some statements written in English to Nnewi dialect. If there is any sentence you wish to know how to say it in Nnewi dialect,you can put it up for interpretation.
1) English: Today,because of what i you did,i will deal with you
Nnewi dialect: Ufuta,maka ifa i melu,mme emeghi ife.
2) Bring that cup to me now
Nnewi: Wotaru m iko ahu fundua.
3) Let's go
Nnewi: Nanje
4) Wait,i'm coming
Nnewi: Wee,ka m bia.

I have a brother from another mother from Nnewi, a proud Nnewi guy. He once told me about the original Nnewi dialect which only the aged people in his village speak till today, and how it is quite different from what is spoken as 'Nnewi dialect' today. He said the original version is quite difficult to understand by younger generations and has quite some differing words from central Igbo. For example, 'fundua' for 'now' compared to 'kita' or ugbu a' pervasive in Igboland.

bigfrancis21: I have a brother from another mother from Nnewi, a proud Nnewi guy. He once told me about the original Nnewi dialect which only the aged people in his village speak till today, and how it is quite different from what is spoken as 'Nnewi dialect' today. He said the original version is quite difficult to understand by younger generations and has quite some differing words from central Igbo. For example, 'fundua' for 'now' compared to 'kita' or ugbu a' pervasive in Igboland.

Yes,i lived with my granny and thats how i learnt the original Nnewi dialects.
Actually,like you said,it is mostly used by aged people but i personally do use it and in some circumstance where i want to sound different,i prefer it too.

When an Nnewi,Amichi speaks you can tell.
Example;oho nmu...its not me.
Oo nge...what is it.

bigfrancis21: I have a brother from another mother from Nnewi, a proud Nnewi guy. He once told me about the original Nnewi dialect which only the aged people in his village speak till today, and how it is quite different from what is spoken as 'Nnewi dialect' today. He said the original version is quite difficult to understand by younger generations and has quite some differing words from central Igbo. For example, 'fundua' for 'now' compared to 'kita' or ugbu a' pervasive in Igboland.

Ndua in Umuoji means now.
Ndeli...late night.
Uchichi..abani
Okongwu...an elderly person.
Onye ulu....a thief.