As an engine runs, the crankshaft seals at the front and rear of the engine tend to wear. The front seal (being easiest to replace) is usually the first to go.
But with the engineering of the PCV system with dynamic vacuum means most people will be unaware of the wear until after The Groove has been applied. This is because the only thing keeping the oil in the engine IS the vacuum! The biggest problem is it is sucking in air at the seal now, aerating the oil (a BAD thing!!!) and the customer doesn't know their engine is wearing out even FASTER.
When you run across an engine that is older than 15 years, advise the customer his seals may be worn and why it MAY become apparent after the groove is applied. Make sure they know it is not a product of the modification process, but because of the age and mileage on the seals and you can save a TON of aggravation and gain a very happy customer!
Ron
