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 investors' portfolios.

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

Hartford International Value R4 (HILSX Quick QuoteHILSX - Free Report) : 1.17% expense ratio and 0.77% management fee. HILSX is a part of the Non US - Equity fund category, many of which will focus across all cap levels, and will typically allocate their investments between emerging and developed markets. HILSX has achieved five-year annual returns of an astounding 17.42%.

Invesco Comstock R6 (ICSFX). Expense ratio: 0.43%. Management fee: 0.38%. ICSFX is a part of the Large Cap Value category, and invests in equities with a market capitalization of $10 billion or more, but whose share prices do not reflect their intrinsic value. This fund has managed to produce a robust 18.32% over the last five years.

T. Rowe Price Blue Chip Growth R (RRBGX): 1.21% expense ratio and 0.55% management fee. RRBGX 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 a five-year annual return of 12.4%, this fund is a well-diversified fund with a long track record of success.

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.