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 break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.

Columbia Small Cap Value I Class Z (CSCZX Quick QuoteCSCZX - Free Report) : 1% expense ratio and 0.81% management fee. CSCZX is a Small Cap Value mutual fund option, which typically invest in companies with market caps under $2 billion. With annual returns of 13% over the last five years, this fund is a winner.

MassMutual Premier Small/Mid Cap Opportunities A (DLBMX Quick QuoteDLBMX - Free Report) : 1.19% expense ratio and 0.58% management fee. DLBMX is a Small Cap Blend mutual fund, and usually targets stocks with market caps of less than $2 billion, letting investors diversify their funds among other kinds of small-cap equities. With yearly returns of 11.57% over the last five years, DLBMX is an effectively diversified fund with a long reputation of solidly positive performance.

Oppenheimer Gold & Special Mineral Y (OGMYX Quick QuoteOGMYX - Free Report) is an attractive large-cap allocation. OGMYX is classified as a Sector - Precious Metal fund, and these mutual funds invest in stocks with a focus on the mining and production of precious metals like gold, silver, platinum, and palladium. OGMYX has an expense ratio of 0.85%, management fee of 0.6%, and annual returns of 12.94% over the past five years.

We hope that your investment advisor (if you use one) has you invested in one or all of the top-ranked mutual funds we've reviewed. But if that isn't the case, it might be time to have a conversation or reconsider this vitally important relationship.