Investing in mutual funds for retirement is never too late. And the Zacks Mutual Fund Rank can be an excellent tool for investors looking to invest in the best funds.

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 investors' portfolios.

Here are the funds that have achieved the Zacks Mutual Fund Rank #1 (Strong Buy) and have low fees.

SEI International Equity F (SIT) (SEITX): 1.09% expense ratio and 0.51% management fee. SEITX is a Non US - Equity fund. Many of these funds like to allocate across emerging and developed markets, and will often focus on all cap levels. With annual returns of 10.41% over the last five years, this fund is a winner.

Goldman Sachs LrgCp Gr Insights R6 (GLCUX) is a stand out amongst its peers. GLCUX is a Large Cap Growth option; these mutual funds purchase stakes in numerous large U.S. companies that are expected to develop and grow at a faster rate than other large-cap stocks. With five-year annualized performance of 15.46%, expense ratio of 0.54% and management fee of 0.51%, this diversified fund is an attractive buy with a strong history of performance.

Franklin Templeton SMACS (FQTEX Quick QuoteFQTEX - Free Report) is an attractive large-cap allocation. FQTEX 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. FQTEX has an expense ratio of 0.08%, management fee of 0%, and annual returns of 13.66% over the past 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.