CC's and Credit Score

[b2m_vw]

I searched and only came up with mostly threads about cancelling cards and how that affects your score. So here's my scenario/question...

Here's my situation:
Credit Union VISA: had for about 8-9 years, my oldest card, $5000 limit, $0 balance
American Express Blue Cash: had for about a year, $2000 limit, $0 balance
Citi Cash Returns MC:had for about 2 years, $4000 limit, right now using this for bills, everything everything I can, paying off in full every month (roughly $600 give or take)
Rent a house from my dad, so I don't get credit help from this as I pay him every month
I have a car loan that I pay towards every month

Now I do NOT plan on cancelling any of them, but I am wondering should I be using the other two for a transaction every month and paying on them to help my credit score. My score is now in the 730s and I would like to continue to raise it.

So should I be charging the other two cards for a transaction (ex like a tank of gas) and paying them as well? Or should I just keep using the one like I am?

[twilk]

It's not going to do much to help your score, but I would use them occasionally and pay them off each month just to ensure the lines stay open. Banks will close inactive credit card accounts.