First time I've tried this product but so far I'm happy with the results. Usually I'm not much of an additive guy but my hyundai 3.8 engine is getting on in mileage. 177k on the odometer right now. I drive mostly highway miles but lately the engine just hasn't been quite as smooth or quiet as it used to be. The motor takes 5.5 quarts so I did an oil change and used this product as my .5 quarts. After running it for a couple hundred miles the engine is smoother and quieter. Much like it used to be. Will continue to use this every other oil change.