This week, the ratings of 9 Oil Gas & Consumable Fuels stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Slipping from a C to a D rating, World Fuel Services Corporation (INT) takes a hit this week. World Fuel Services Corporation is engaged in the marketing and sale of marine, aviation and land fuel products and related services on a worldwide basis. The company also gets F’s in sales growth. For more information, get Portfolio Grader’s complete analysis of INT stock.

SemGroup Corporation Class A (SEMG) declines this week from a D to a F. SemGroup Corporation Class A moves energy through a network of pipelines, terminals and storage tanks. The company also gets F’s in sales growth, earnings growth, earnings revisions, earnings surprise, earnings momentum, and free cash flow. For more information, get Portfolio Grader’s complete analysis of SEMG stock.

HollyFrontier Corporation’s (HFC) rating weakens this week, dropping to a F versus last week’s D. HollyFrontier Corporation refines, transports, stores and markets petroleum products. The company also gets F’s in sales growth, earnings growth, earnings revisions, earnings surprise, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of HFC stock.

This is a rough week for Delek Logistics Partners LP (DKL). The company’s rating falls to D from the previous week’s C. The company also gets F’s in sales growth and earnings revisions. For more information, get Portfolio Grader’s complete analysis of DKL stock.

This week, Alliance Holdings GP, L.P. (AHGP) drops from a D to a F rating. Alliance Holdings GP, L.P. produces and markets coal to utilities and industrial users in the United States. For more information, get Portfolio Grader’s complete analysis of AHGP stock.

Teekay LNG Partners L.P. (TGP) is having a tough week. The company’s rating falls from a D to a F. Teekay LNG Partners L.P. provides marine transportation services for liquefied natural gas, liquefied petroleum gas and crude oil. The company also gets F’s in earnings growth and free cash flow. For more information, get Portfolio Grader’s complete analysis of TGP stock.

Frontline Ltd. (FRO) gets weaker ratings this week as last week’s C drops to a D. Frontline Ltd. owns a fleet of very large crude carriers and Suezmax tankers that transport crude oil and oil products between ports. The company also gets F’s in earnings surprise. For more information, get Portfolio Grader’s complete analysis of FRO stock.

Petroleo Brasileiro SA Sponsored ADR (PBR) experiences a ratings drop this week, going from last week’s C to a D. Petroleo Brasileiro SA Sponsored ADR explores for and produces oil and natural gas. The company also gets F’s in sales growth, earnings growth, earnings revisions, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of PBR stock.

This week, Aemetis, Inc.’s (AMTX) rating worsens to a D from the company’s C rating a week ago. The company also gets F’s in sales growth, operating margin growth, and free cash flow. For more information, get Portfolio Grader’s complete analysis of AMTX stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.