to insist on "...& I" rather than "me and..."

[Aigle]

DC1 (Y3) has started using "me and 'Oliver' " rather than the grammatically correct " 'Oliver' and I" ... AIBU to insist that he uses correct English at this age. I imagine that many of his friends are using the awful "me and" construction and that he has picked it up from them. I thought initially that we would require correct usage at home, and let him use the vernacular at school, but a friend has advised that is should all (correct) or nothing (whatever).

Depends on the sentence. "Oliver and I" isn't always correct.

I was just about to say the same as ecclesvet, it's not always correct and I find misuse of '...and I' worse than overuse of 'me and...'

As long as you only insist of using '... and I' when that is correct, and do not overrule '... and me' when that is correct, YANBU.

There are few things I have less tolerance for than a pedant who is wrong.

(Obviously, Muphry's Law applies to this post).

Most children start to use 'alternative' grammar and pronunciation when they are exposed to alternatives through their peer group. It is a normal process, and they usually adhere to the style they grew up with.
However, as use of "...and I" is not always correct, are you possibly 'over correcting'?

This may help
www.betterwritingskills.com/tip-w026.html

It doesn't depend on the sentence when the personal pronoun I and the noun (the friend) form the subject of the sentence. I am asking about that situation.

I wouldn't object to "John's father drove 'me and Oliver' home" (although I would probably suggest 'Oliver and me' in that case.

If you know the difference between and subject and an object then I would correct, yes.

I think it's important that he knows the difference and how to determine whether Oliver and I or Oliver and me is correct. However I think it's more important in writing rather than everyday speech and wouldn't worry about correcting him every time he slips up.

Tee hee for Muphry's Law!

I don't think "Me and Oliver are going to the park" is that heinous, and I disagree with your friend who says it's all correct or nothing. Children can move backwards and forwards between grammatically correct English and looser English. I'd tell him mildly that "Oliver and I" is better in that context, but I wouldn't make a feature of it. Children being children, he might well do it to annoy you - my own dd does this with glottal stops instead of "t"s because she finds it funny that I give her the death stare.

How will you stop him using the vernacular at school anyway? You won't be there.

I actually don't think it's a very good idea to explicitly correct the grammar of a young child. The general advice is to use the correct form yourself, and to repeat back what has been said but using the right construction. You need to be encouraging him to talk and express himself, not making him anxious about getting it wrong.

Thanks for the link JRY I've never been certain when I should use me or I, now I know!