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 take a look at some of our top-ranked mutual funds with the lowest fees.

Franklin Convertible Securities Adviser (FCSZX Quick QuoteFCSZX - Free Report) : 0.58% expense ratio and 0.46% management fee. FCSZX 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. With annual returns of 11.15% over the last five years, this fund is a winner.

Ivy Large Cap Growth I (IYGIX Quick QuoteIYGIX - Free Report) : 0.64% expense ratio and 0.6% management fee. IYGIX is a part of the Large Cap Growth mutual fund category, which invest in many large U.S. companies that are expected to grow much faster compared to other large-cap stocks. With yearly returns of 11.41% over the last five years, IYGIX is an effectively diversified fund with a long reputation of solidly positive performance.

Ivy Large Cap Growth I (IYGIX Quick QuoteIYGIX - Free Report) : 0.64% expense ratio and 0.6% management fee. IYGIX is a part of the Large Cap Growth mutual fund category, which invest in many large U.S. companies that are expected to grow much faster compared to other large-cap stocks. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 11.41% over the last 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.