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.

Frost Growth Equity Investor (FACEX Quick QuoteFACEX - Free Report) : 0.88% expense ratio and 0.5% management fee. FACEX is a Large Cap Growth mutual fund, and these funds invest in many large U.S. firms that are projected to grow at a faster rate than their large-cap peers. With annual returns of 16.12% over the last five years, this fund is a winner.

JPMorgan US Equity Fund R5 (JUSRX Quick QuoteJUSRX - Free Report) . Expense ratio: 0.54%. Management fee: 0.4%. JUSRX is part of the Large Cap Blend section, and these mutual funds most often invest in firms with a market capitalization of $10 billion or more. By investing in bigger companies, these funds offer more stability, and are often well-suited for investors with a "buy and hold" mindset. This fund has managed to produce a robust 16.82% over the last five years.

T. Rowe Price Cap Appreciation Adviser (PACLX Quick QuotePACLX - Free Report) . Expense ratio: 0.96%. Management fee: 0.59%. Five year annual return: 11.09%. PACLX, an All Cap Value option, is a type of mutual fund that buys stakes in companies in all three valuation categories.

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.