I have also been using Yield, by Chemsearch. I have also used most their products, since I was a salesman and worked for them. Yield was the best product I had ever used. However, I now have found a product,that is at least 3 times better, and it came as a shock to me. It is called Royal Purple Maxfilm. I have an old car where my right door couldn't bee locked with the key, manually(it probably was rusted). It sat for more than two years. I tried CRC, WD40, Yield, Feed Way Extra and several other Chemsearch products. It never came loose. Until two weeks ago! I went to buy some RP engine oil, and the guy who sells it, told me about Maxfilm. I just said Ha,Ha and told him about Yield and the other products from Chemsearch. Since my car was just 10 yards away, I said to him that if it did loosen up the door, I would buy it. I took the bottle, sprayed it in the keyhole(like I had done with all the other stuff), waited 10 seconds and UNLOCKED the door. I really didn't expect this to happen. Well, I bought the spraycan, and it have made a big difference in the two cars we own, as well as the bikes and everything else that need lubrication. This is without doubt, the best penetrating and lubricating oil I have ever tried. Now, it is easy to work on the car.