505 CRO Oil System Treatment - 12 oz Engine Oil Additive - Cleans Sludge, Reduces Emissions, Quiet Smooth Idle & Restores Performance in High-Mileage Gas & Diesel Engines

It does 100 percent as it says it will, few products do.

It improves the engine life, and clean all residue of sticky oil and dirt.

Disappointed as I followed the directions to the letter and for this price, I was expecting more than crickets. I guess it's for individuals that don't do regular oil changes because I wasted 20 mins of fuel in a 5.7 liter v8 for the oil to smell different upon changing, that's all.

I have a 2016 Jeep Cherokee with 330,000 miles. After amazing results using ATF Chemical 505 CRF Fuel System Treatment (see separate review), I ordered this ATF Chemical 505 CRO Oil System Treatment. I believe my results are of particular interest because I did not perform the treatment by adding the product to dirty old oil, as you would right before an oil change, but I added the product to fresh clean oil right after an oil and filter change. Wait till you see what happened. The instructions say to add the product to your engine's oil, run the engine at "high idle" (some mechanics say @ 2,000 RPM) for 10 minutes or more, then drain the treated oil, remove the oil filter and install a new filter and new oil. However, what I did was last night I added the product to the fresh oil that was in my car, ran the engine at regular idle speed (say 750 RPM) for 10 minutes, turned off the engine and let it sit overnight. This morning I started the engine and moderately drove the car (2,000 RPM max) for 40 minutes, parked the car and let it sit for a few hours, then drained the oil. I was very curious to see what the oil looked like when I drained it. Would it look like the brand new oil that I had just put in the car? The answer is an emphatic NO - the oil was PITCH BLACK - it looked like old oil coming from an engine that was overdue for an oil change. In my opinion this stuff does what it was designed to do. It cleaned out the built-up carbon deposits internal of my engine. After installing a new filter and new oil I drove the car today as normal for about 90 minutes around town and highway. It is probably too soon to tell but I think the engine runs smoother and quieter. I will now be using these products on all my vehicles (5 cars/trucks, 4 motorcycles) and recommending this product to everyone. I am SO glad I found out about these products from a mechanic on YouTube who says these are "products your mechanic does not want you to know about" and that they will "make your vehicle last 3x longer". I have no doubt this is so. Easy to use. Does as advertised. Worth every penny.

Manufacturer has two similar products; one for oil, one for fuel. This review is for the oil additive. I also saw this via with Scotty on YouTube. The only reason I'm giving 4 starts because the top is a little difficult to take off. Don't know about or why any complaints regarding this product. It's great! Our success came even before we were done, and I'm sure I did it wrong. I believe you're supposed to add it, run your engine high, empty by changing your oil, and enjoy. I did this over a 2 day stint, with 2 round trips to work (apprx 25 min's each way) and one 15 min trip to the mechanic to have oil changed. I added only ½ on day one, and we could DEFINITELY hear a difference with the engine being more quiet after the 1st day return trip home. I added the remaining amount for 2nd day trip. i will update this review after the official oil change, but even after JUST first day of cleaning we can definitely hear an improvement. ADDITIONAL PRO TIP: Regarding the difficult top. The product looks like it has one, but actually has TWO type of tops! I cant say how the first top is "supposed" to come off, but I took a screw driver and gently pried up into and around and around the edge and finished - twist /pulled off. THEN... there's a second top that has one of those plastic ring types to pull /tear clear of the can. It's still tough, so I took a screw driver again - put it through the ring and twisted it off gently until it stretched and broke out.