I've never used it and have had four vaginal births with zero complications or tears. I think it might be helpful for some women, but definitely isn't required. Preparing to give birth in a physiologically appropriate position is more likely to have a big influence over the outcome and tearing, etc. Squatting, side-lying, all-fours, half-kneeling and even standing are all excellent choices for pushing! Just do what comes naturally and listen to your body, and make sure your OB or midwife knows that you want to be allowed to do that if there is no life-threatening emergency. A dr who can't deliver a baby in any position but reclining is sorely lacking in basic skills. Avoiding unnecessary interventions and pushing only with the urge (no matter how impatient you feel, or how rushed others make you feel) is important as well. These things help prevent damage to your bottom area.
My aunt actually told me to eat alot of salad with EVOO and it would help them slide right out, she had three boys all natural, so I guess she new what she was talking about, I never tried it I hate Salad LOL
Sit in a semi-reclined position in a warm, comfortable area, spreading your legs apart. Lubricate your fingers, thumbs, and perineal area with vitamin E oil (from punctured vitamin E capsules), pure vegetable oil, or personal lubricant. Don't use baby oil, mineral oil, or petroleum jelly.