I recently ran out of Hops #9 oil, and had some left over BMW fully synthetic 5w-30 engine oil. I refilled the bottle with the BMW oil, and used it to oil my glock a few months ago. I just went to the range, and shot 300 rounds. When I got home, I field stripped my glock, and realized that the barrel and slide rails still were wet with oil. I have never previously found wet oil in a glock that had hundreds of rounds though it. Fully sunthetic engine oil works great, lasts long, and is 15 to 20 times cheaper then Hops gun oil.