There is never a wrong time to invest in mutual funds for retirement. So, if you're still looking for the best mutual funds, the Zacks Mutual Fund Rank can be a great guide.

How can you tell a good mutual fund from a bad one? It's pretty basic: if the fund is diversified, has low fees, and shows strong performance, it's a keeper. Of course, there's a wide range, but using the Zacks Mutual Fund Rank, we've found three mutual funds that would be great additions to any long-term retirement investors' portfolios.

Let's learn about some of Zacks' highest ranked mutual funds with low fees you may want to consider.

AllianzGI Convertible Fund IS (ANNPX Quick QuoteANNPX - Free Report) : 0.71% expense ratio and 0.57% management fee. ANNPX is a Convertible Bonds mutual fund, and these funds are unique in the fixed income world; these securities have components of both fixed income and equity, making them hybrid securities. ANNPX has achieved five-year annual returns of an astounding 9.95%.

Diamond Hill Select I (DHLTX Quick QuoteDHLTX - Free Report) . Expense ratio: 0.87%. Management fee: 0.7%. DHLTX is a Large Cap Value fund. These funds invest in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. This fund has managed to produce a robust 9.8% over the last five years.

ClearBridge Large Cap Growth O (LCMMX Quick QuoteLCMMX - Free Report) is an attractive large-cap allocation. LCMMX is a Large Cap Growth option; these mutual funds purchase stakes in numerous large U.S. companies that are expected to develop and grow at a faster rate than other large-cap stocks. LCMMX has an expense ratio of 0.7%, management fee of 0.61%, and annual returns of 10.48% over the past five years.

There you have it. If your financial advisor had you put your money into any of our top-ranked funds, then they've got you covered. If not, you may need to talk.