In November, 2004 I went back to the same Jiffy Lube on Park Avenue in Worcester, MA. I had almost forgotton about the previous incident, but happened to count the visible quarters on my way over to the Jiffy Lube -- there were 18 visible quarters, plus a lot of other change. When I left, it was again visibly lower. Few quarters were visible; a count of all the coins in the coin holder showed there were only 9 quarters left. Since I didn't count all the coins before I got to Jiffy Lube, I can't say how much was stolen, but I estimate it was about $5-10 worth (there were also a number of $1 coins that were missing; it is unclear whether they were stolen on this visit or the previous visit).
In November, 2004, the day after getting the oil change, I found that $3 in bills that I had in the glove compartment were stolen, too. In case there was any doubt that it was stolen by someone at Jiffy Lube, the old "oil change sticker" was sitting where the bills had been. The stupid thief was so excited at the $3, he dropped the old sticker that he was supposed to throw out, and forgot about it. Since there is absolutely no need for a Jiffy Lube employee to go into the glove compartment, this wasn't simply a case of an underpaid employee be tempted by loose change in his sight; this thief was searching through the car for items to steal.
In both April, 2004 and November, 2004, a Jiffy Lube employee told me that since my car had about 79,000 miles on it, I was required to pay an extra $20 for their special "High Mileage" oil. I consider this to be a scam, pure and simple. They are charging more money for older vehicles, for absolutely no reason other than profit. If I wanted their High Mileage oil instead of standard oil, it's fine to charge more for it. If High Mileage oil was required for my car per the manufacturer, it's fine to insist on it. But I consider forcing someone to pay an extra $20 for something that isn't required to be a scam.
In my letter, I mentioned that I had the old "oil change sticker" that could be sent to the authorities if needed for fingerprinting. The owner in his letter asked me to give it to him (no, sorry, I won't give evidence of a crime to the company whose employee committed it; law enforcement is in charge of fingerprinting).
His response to the PCV valve was that they only go by the time/mileage of the last change according to their database. While this may be the official policy, there is a big difference between a salesperson showing you something that they say desparately needs to be replaced, as opposed to a salesperson saying that their records show that it has been a long time since the PCV was replaced.
The owner implied that they had not identified the thief, but he neglected to mention whether  the manager lied to me and did not review the videotapes, or  the videotapes could not identify the thief (and why they could not identify the thief).
For advice on oil changes, you can go to www.oilchangeadvice.com.