I have a 1990 ford escort with a 1.9liron block in it and have owned it since 25000kms.I use quaker state synthetic in every engine in my hosehold and have used it in the escort since the first day that I had it in the driveway.Not what you call a car with a lot of initial quality in it.I also live in the most corrosive part of north america,the east coast of Canada.I change the oil at the proper intervals and maintain the car as best as I can.790000kms later it still works like a charm and is all original under the hood except for the starter and the rad.My mechanic cant beleive how little wear it shows,certainly has been an excellent product for me, I'll never use anything else.