Bests & Worsts Reviews from Amazon

Scotty Kilmer said AT-205 is watery and harmless because it’s a polymer. I’d never heard of a watery polymer. ATP calls it a plasticizer. A plasticizer is a solvent used to make a polymer more rubbery by loosening the bonds between molecules. This one seems to be diethylene glycol monoethyl ether. ATP says it won’t harm internal components. The website says it’s compatible with conventional and synthetic oils, ATF, gear oil, power steering fluids, and hydraulic oil. It has a 3-minute video, which for 5 seconds presents a chart of recommended amounts with three columns of seven figures each. Do they really expect you to digest that in 5 seconds? For those 5 seconds there are two lines of print below the chart. If you pause the video, they are grayed out and covered with ads. I had to replay that segment several times to be sure I understood. They say, “Recommended use is approximate due to blending properties with oil. No risk if slightly over treated.” Contrary to their assurances, this implies a risk. It seems as if ATP did not intend for the viewer to see the warning. The video devoted a minute to showing the representative open a hood, pour in a bottle of AT-205, and close the hood. An Amazon customer reported that after he did so, the concentrated solvent in the oil pan caused the paint to come loose and clog the screen on his oil pump. It’s not a new product, but the video didn’t recommend running the engine to mix the solvent. Buyer beware! My 35-year-old car occasionally smoked on startup. Probably the valve seals were worn or shrunken. Deposits from oil additives damaged spark plugs and O2 sensors. AT-205 would be a lot cheaper than having the seals replaced, but I was afraid AT-205 could expand seals more than necessary, and that could accelerate wear. For 4 quarts, ATP recommends 6oz, or 180ml. The oil would have about 4.7% solvent. I decided to try 100ml (about 2.7%) and add the rest if necessary. I used a polypropylene measuring cylinder. It measures precisely, pours as neatly as using a funnel, and rinses better than glass. I ran a short errand to mix it and ran another short errand the next day. Then I cleaned the grime below the valve cover gasket, which leaked. Months have passed. The gasket has not leaked, and I haven’t seen or smelled any oil smoke. My riding mower was 25 years old. An unseen oil leak caused chaff to accumulate on the cooling fins, hidden under the housing. That interfered with the flow of cooling air. It often smoked on startup. I didn't know if leaky rubber seals caused either problem. I added 25ml of AT-205, about 1% of the oil in the crankcase. I mowed a few minutes to mix it. The next day, I cleaned off the oil and grime. in the months since then, the engine has stayed clean, and it hasn't smoked on startup. The next time I have a leaky machine, I’ll start with 0.5% to minimize risk. I can always add more. Update: Scotty was right about using AT-205 to preserve plastic parts. My positive battery terminal protector uses a "living plastic" hinge. It had stiffened so that it wouldn't stay down. A couple of applications of AT-205 improved it. My big concern was the duct from the MAF meter to the throttle. It had become brittle over the years. It looked impossible to fabricate a new one with all those hose fittings. I've applied AT-205 three times. A little goes a long way. I put a teaspoon or so in a cup and apply it with a cotton ball. I also wipe it on pneumatic hoses. Plastic absorbs it slowly, so I check after a couple of days. Skin absorbs it readily, but research has shown it's harmless (pharmacologically inert). Another update: The manufacturer of my mower engine recommends oil changes according to engine hours and doesn't mention time intervals. I waited two years. During that time, the oil continued to feel and smell okay. Two weeks after the oil change, I got a lot of oil smoke on startup. I had assumed that the solvent not immediately absorbed by the rubber had evaporated from the old oil long ago. Apparently it had stayed in the oil, continually refreshing the old seals. Because I'd used it conservatively, I had some on hand to supplement the new oil.