It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

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.

Goldman Sachs Large Cap Value IR (GSVTX Quick QuoteGSVTX - Free Report) : 0.79% expense ratio and 0.75% management fee. GSVTX is a Large Cap Value mutual fund, which invests in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. With annual returns of 11.31% over the last five years, this fund is a winner.

JPMorgan Mid Cap Equity Fund A (JCMAX Quick QuoteJCMAX - Free Report) . Expense ratio: 1.14%. Management fee: 0.65%. JCMAX is a Mid Cap Blend mutual fund, and usually features a portfolio with stocks of various styles and sizes, allowing for diversification within a strategy that focuses on mid cap companies. This fund has managed to produce a robust 11.82% over the last five years.

Fidelity Trend Fund (FTRNX Quick QuoteFTRNX - Free Report) : 0.52% expense ratio and 0.48% management fee. FTRNX is a Global - Equity mutual fund. These funds invest in large markets like the U.S., Europe, and Japan, and operate with very few geographical limitations. With a five-year annual return of 18.99%, this fund is a well-diversified fund with a long track record of success.

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.