Well my valve covers don't leak anymore so they've done their job. The 4.0 V6 in my Explorer doesn't lend itself to such an easy repair, which is why I ended up paying to have it fitted (oh! back when you didn't have to take half a car apart to replace simple parts!). The hardest part is just getting to the valve covers, once removed it's not a difficult task. You can't go wrong with the Fel-Pro.