Sir Elton John - who just adopted a baby with husband David Furnish - decided to vent to Rolling Stone magazine about pal Billy Joel's apparent problems with alcoholism.

Here's what the 63-year-old Grammy winner, who went to rehab in 1990 for drug and alcohol abuse, said to RS:

    "He's going to hate me for this, but every time he goes to rehab they've been light. When I went to rehab, I had to clean the floors. He goes to rehab where they have TVs.

    I love you, Billy, and this is tough love. Billy, you have your demons and you're not going to get rid of them at rehab light. You've got to be serious. People adore you, they love you and respect you. You should be able to do something better than what you're doing now. At the end of the day, he's coasting. I always say, 'Billy, can't you write another song?' It's either fear or laziness. It upsets me. Billy's a conundrum. We've had so many canceled tours because of illnesses and various other things, alcoholism."

In response, Billy Joel told Us, "I've worked with Elton for such a long time and I've enjoyed our relationship too much to let something as random as these comments change my affection for him. Elton is just being Elton."

John also talks about his friendship with rapper Eminem: "When David and I had our civil partnership, he sent us a present... two diamond c--k rings."

And he reveals that super-conservative talk show host Rush Limbaugh "was one of the first people to congratulate us on the baby."

John performed at Limbaugh's wedding in summer 2010 for a reported $1 million fee.