Do engine treatments like Slick 50 really work?

Are any of these engine treatments worth the money at all like Slick 50 or any other type of product like this?


No. They’re all snake oil.

If they were worth anything car manufacturers would specify their use.

Not in my opinion. Appropriate oil changes is all you need. Are you trying to solve a problem?

I would say no, but advise you to search for “Slick 50” and read supporting documents there.

About 20 years ago, I decided Slick 50 sounded like a good idea, so I put some into a brand new Jetta GLI, with no ill-effects. I remember it was expensive, and at the time, I think it had teflon in it. Teflon in a crankcase is a bad idea; it can clog journals quickly, and do the opposite of reducing wear. Luckily, that problem never happened for me.

Just read your owner’s manual and follow the recommendations there. That’s your best course of action. If it says “5W-20 synthetic, service grade SM”, use that. The manual for my 96 Maxima specifically recommends 5W-30, non-synthetic oil, so that’s what I use.

Some manuals even go so far as to specify using no additives.

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My Dodge truck and Mazda car now have over 100K miles and was looking more in the coming years if this would help extend the life of my engine or some product. I do change oil at 3K miles. So far no engine issues.
Maybe if it not broke don’t try to fix it.


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The chances of your car dying a premature death because you didn’t use any oil additives are so slim, I wouldn’t worry about it. How often you change your oil and whether you use the proper oil are a much bigger factors.

It is much more likely your automatic transmission will fail before your engine. If you are looking for a way to extend the life of your car, I would say most people know to change the oil on a regular basis, so I would look at the cooling system and the transmission. Having the coolant changed every two years and having your transmission properly serviced every 30,000 miles could help your cars last longer. If you have an automatic transmission, that would mean draining the fluid, dropping the pan, and cleaning the filter, not just draining and refilling, and not having the fluid flushed.


Most of the claims made on the sides of additive cans can not be proven one way or the other. For sure, the most important factor is keeping your engine full of clean oil. If your are 2 quarts low and you haven’t changed your oil in 8000 miles, additives have nothing to offer…If your crankcase is full of clean oil, they have nothing to offer either.

In certain situations, special-purpose products can provide a benefit…Highly solvent “engine flushes”, stop-leaks, products that reduce oil burning, these can have a place as cars drift into their “sunset years”…

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If you’re changing every 3000 miles, I will claim that there is no additive that will add one mile to your engine’s life, as far as wear is concerned. Do like Whitey says, focus on the tranny and brakes and you’ll see 200k.

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My Dodge truck and Mazda car now have over 100K miles and was looking more in the coming years if this would help extend the life of my engine or some product.

Myself and many others here have had cars last well past 300k miles WITHOUT any of those products. So you expecting Slick-50 make the car last 500k miles???

Slick 50 worked as designed. It made a lot of money for the manufacturer and sorry to say damaged a lot of engines.

If it not broke Don’t fix it. If it is broke, Slick 50 will not fix it.

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There is no such thing as magic anything. Some of the friction reducing “magic in a bottle” stuff will do something. Many are chlorinated paraffins. What they do (maybe) is save you $6 for $25 in costs. Most are correct here in that the best thing that they do is clean your wallet.

There are additives that can be used to correct given issues, but without issue, there’s no reason to use them. One product that I used every 75k or so is Auto-Rx. It will clean long term deposits out of the ring area. Every used car purchased gets a treatment and all owned from new cars get it somewhere around 75k-80k. It’s also good for problematic engines or one acquired in an unclean state. The good thing about it is that it’s composed of 3 esters and isn’t $0.25 worth of solvent and $15 worth of marketing and advertising.

Back in 1965 I bought the first car I ever owned with a positive crankcase ventilation. When I was looking at the engine before I purchased the car, I noticed the hose going from the PCV valve on the rocker arm cover to the base of the carburetor. When I asked the salesman about it, he said that it was to reduce the smog. I told him that I never remembered any smog in our area. “Works pretty well, doesn’t it?” he replied. I feel the same about the testimonials about Slick 50 and other such products. The cars would go 150,000 miles whether or not Slick 50 was used just as my part of the nation wouldn’t have a smog problem even if all cars still had road draft tubes.

I have only anecdotal evidence but am convinced that this product works. #1 An old Mazda 323 with about 280,000 miles on it. You could not do a 1 - 2 shift into second without grinding the gears. (Typically worn out syncros) I skeptically added Slick 50 for gear boxes and the grinding was immediately fixed. #2 1988 Honda Accord. Came down my super bumpy driveway and bottomed out. Left my Honda running for at least 20 minutes not knowing that I had put a hole in the oil pan. Came out and saw a huge puddle of oil and the car still running with the oil light on. Shut it off, fixed the oil pan, and the car ran for at least another year or 2 before it was totaled by another car in an accident. This is about big corporation politics, IE Dupont!

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I use synthetic oil in most of my cars and run 7,500 mile oil change intervals with no issues or sludging. I don’t own a single oil burner (my 04 Sienna with 215,000 uses half a quart every 6,000 miles). My son’s 200,000 mile Camry gets high mileage oil due to some gasket leakage and a 5,000 mile interval (my dad owned the car for most of it’s life). I never put anything in the crankcase except motor oil. Period. My engines outlast my vehicles due to my life in the snowbelt of New York State.

Discredited 20 years ago:

Why would someone join and post a testimonial about snake oil to a 6 year old thread ?

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Car Talk Lackey
Re: Fuel and Oil Additives

I agree with mcparadise. It is still Snake Oil which is not beneficial. Save your money.

slick 50 = :snake: :oil: