NEW YORK (TheStreet) -- Cramer said he's worried about what's happening with three stocks: Volkswagen (VLKAY) , Glencore (GLCNF) and Petrobras (PBR - Get Report) . Cramer made the comment on the floor of the New York Stock Exchange while answering viewers' Twitter (TWTR - Get Report) questions Friday.

Volkswagen is embroiled in an emission scandal and is changing its leadership. Commodity company Glencore's stock has been sliding all this week. As for Petrobras, Cramer said he believes if oil prices don't go up, the company will have to do a debt restructuring.

Cramer said these are bigger worries than a possible Federal Reserve interest rate hike, which he said he'd like to see by year end. Cramer doesn't want to see the Fed raise rates in October due to concerns about China, but he also said that Nike's (NKE - Get Report) earnings made him feel better about the Chinese consumer.

Cramer's second question was from a viewer who wanted to know if an investor already owns Caterpillar (CAT - Get Report) , whether the stock should be sold or held, in light of this week's news. Cramer said Caterpillar's earnings power is much lower, and he would feel more comfortable if the company's stock was trading in the $50 range.

Cramer was also asked why he prefers Wells Fargo (WFC - Get Report) over JPMorgan Chase (JPM - Get Report) , and he answered that he wants an American bank, without overseas exposure. He added that 98% of Wells Fargo's business is domestic.

One viewer asked Cramer whichcybersecurity stock was the best of breed -- CyberArk (CYBR - Get Report) , FireEye (FEYE - Get Report) , Palo Alto (PANW - Get Report) or Fortinet (FTNT - Get Report) ? Cramer responded that Palo Alto is the best of its breed, but FireEye is the least expensive.

Another viewer asked for Cramer's thoughts on Scotts Miracle-Gro (SMG - Get Report) . Cramer said he's not a big fan, and the stock has traded up and down. He added, "I don't like to use chemicals on my tomatoes."

Finally, Cramer was asked whether Wynn Resorts (WYNN - Get Report) was a safe bet at its current level or too much of a gamble. Cramer said while Steve Wynn is a remarkable operator, he recommends MGM Resorts (MGM - Get Report) over Wynn because of falling gambling revenues in Macau.

Cramer is portfolio manager of Action Alerts PLUS.Send your Twitter questions to him using #CramerQ.

At the time of publication, Jim Cramer's charitable trust Action Alerts PLUS was long TWTR and WFC.