SAN ANTONIO, TEXAS -- I took my car to the Valvoline Instant Oil change location at 19150 Stone Oak Pkw. in San Antonio for my oil change. I have been using this location regularly since moving here several years ago. A few oil changes ago they asked me about using a synthetic oil since I tend to go longer between oil changes and it sounded like a good idea. Everytime I have had my oil changed I have been asked if I wanted the synthetic oil. This last time, I was never asked. When the technician came to show me the oil level in my car I asked him if he had used synthetic oil because I was never asked. He became silent and didn't know the answer. It seems to me that if he is the one adding the oil to my car that he should know what he used. He thought about it and then said yes. Not believing him I asked him if he was sure and he said yes. He said my car would be ready in a few minutes and walked off. Not knowing that I was behind him I overheard him telling the employee checking me out to change it to synthetic. Because I had no way of proving it at the time, I paid and left. I sent a letter to the customer service advising them how I felt that I had been stolen from and never received a reply from them other than their automated reply to let me know that someone would be contacting me. I have since had my car checked out and it was determined that synthetic oil was NOT used in my car, proving that Valvoline steals from it's customers, knows that their employees do and don't care.