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.

The best way to shortlist great mutual funds is to ensure solid performance, diversification, and low fees. Some are better than others, but utilizing the Zacks Mutual Fund Rank, we have identified three mutual funds that could be solid additions to one's retirement portfolio.

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

American Funds Investor Company of America R5 (RICFX) has a 0.31% expense ratio and 0.23% management fee. RICFX is classified as a Large Cap Blend fund. More often than not, Large Cap Blend mutual funds invest in companies with a market cap of over $10 billion. Buying stakes in bigger companies offer these funds more stability, and are well-suited for investors with a "buy and hold" mindset. With yearly returns of 15.66% over the last five years, this fund clearly wins.

Fidelity Value Fund (FDVLX): 0.68% expense ratio and 0.67% management fee. FDVLX is a Mid Cap Value mutual fund, which targets medium-sized companies with a market cap between $2 billion and $10 billion. With yearly returns of 12.61% over the last five years, FDVLX is an effectively diversified fund with a long reputation of solidly positive performance.

Causeway Global Value Institutional (CGVIX Quick QuoteCGVIX - Free Report) . Expense ratio: 0.85%. Management fee: 0.8%. Five year annual return: 14.91%. CGVIX is a Global - Equity mutual fund investing in bigger markets like the U.S., Europe, and Japan; these kinds of funds aren't limited by geography.

These examples highlight the fact that there are some astonishingly good mutual funds out there. If your advisor has you in the good ones, bravo! If not, you may need to have a talk.