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Slick 50 (engine oil additives)

Slick 50 and other engine oil additives supposedly reduce engine wear and increase fuel efficiency.

You may have heard the commercial or seen the ad:

Multiple tests by independent laboratories have shown that when properly applied to an automotive engine, Slick 50 Engine Formula reduces wear on engine parts. Test results have shown that Slick 50 treated engines sustained 50 percent less wear than test engines run with premium motor oil alone.

There are about 50 other products on the market which make similar claims, many of them being just duplicate products under different names from the same company. The price for a pint or quart of these engine oil additives runs from a few dollars to more than $20. Do these products do any good? Not much. Do they do any harm. Sometimes.

What's in these miracle lubricants, anyway? If they're so wonderful, why don't car manufacturers recommend their usage? Why don't oil companies get into the additive business? Where are these studies mentioned by Petrolon (Slick 50)? Probably in the same file cabinet as the tobacco company studies proving the health benefits of smoking.

The basic ingredient is the same in most of these additives: 50 weight engine oil with standard additives. The magic ingredient in Liquid Ring, Matrix, QM1 and T-Plus from K-Mart is Polytetrafluoroethylene. Don't try to pronounce it: call it PTFE. But don't call it Teflon, which is what it is, because that is a registered trademark. Dupont, who invented Teflon, claims that "Teflon is not useful as an ingredient in oil additives or oils used for internal combustion engines." [new] According to the Slick 50 website, Slick 50® Supercharged Synthetic Engine Treatment no longer contains PTFE. Slick 50® Recharged High Mileage Engine Treatment contains a small amount of PTFE. [/new]

PTFE is a solid which is added to engine oil and coats the moving parts of the engine.

However, such solids seem even more inclined to coat non-moving parts, like oil passages and filters. After all, if it can build up under the pressures and friction exerted on a cylinder wall, then it stands to reason it should build up even better in places with low pressures and virtually no friction.

This conclusion seems to be borne out by tests on oil additives containing PTFE conducted by the NASA Lewis Research Center, which said in their report, "In the types of bearing surface contact we have looked at, we have seen no benefit. In some cases we have seen detrimental effect. The solids in the oil tend to accumulate at inlets and act as a dam, which simply blocks the oil from entering. Instead of helping, it is actually depriving parts of lubricant"

In defense of those additives that still use PTFE, tests done on a Chevy 6 cylinder engine by the University of Utah Engineering Experiment Station found that after treatment with the PTFE additive the test engine's friction was reduced by 13.1 percent, the output horsepower increased from 5.3 percent to 8.1 percent, and fuel economy improved as well. Unfortunately, the same tests concluded that "There was a pressure drop across the oil filter resulting from possible clogging of small passageways." Oil analysis showed that iron contamination doubled after the treatment, indicating that engine wear increased (Rau).

the FTC and Slick 50

In 1997, three subsidiaries of Quaker State Corp. (the makers of Slick 50) settled Federal Trade Commission charges that ads for Quaker State's Slick 50 Engine Treatment were false and unsubstantiated. According to the FTC complaint, claims such as the following made in Slick 50 ads falsely represented that without Slick 50, auto engines generally have little or no protection from wear at start-up and commonly experience premature failure caused by wear:

"Every time you cold start your car without Slick 50 protection, metal grinds against metal in your engine."

"With each turn of the ignition you do unseen damage, because at cold start-up most of the oil is down in the pan. But Slick 50's unique chemistry bonds to engine parts. It reduces wear up to 50% for 50,000 miles."

"What makes Slick 50 Automotive Engine Formula different is an advanced chemical support package designed to bond a specially activated PTFE to the metal in your engine."

In fact, the FTC said, "most automobile engines are adequately protected from wear at start-up when they use motor oil as recommended in the owner's manual. Moreover, it is uncommon for engines to experience premature failure caused by wear, whether they have been treated with Slick 50 or not." 

zinc: good for the common cold & your car's engine

Another type of additive is zinc dialkyldithiophosphate. Zinc-d is found in Mechanics Brand Engine Tune Up, K Mart Super Oil Treatment, and STP Engine Treatment With XEP2, among others. The touting of zinc-d as a special ingredient in engine oil additives is a little like the Shell ads which touted "Platformate." (Most gasoline has similar additives but under different names.) Zinc-d is an additive in most, if not all, major oil brands. The wonder oils just put more of the stuff in a 50 weight engine oil. It would be useful if your engine were ever operated under extremely abnormal conditions where metal contacts metal: "the zinc compounds react with the metal to prevent scuffing, particularly between cylinder bores and piston rings....unless you plan on spending a couple of hours dragging your knee at Laguna Seca, adding extra zinc compounds to your oil is usually a waste.... Also, keep in mind that high zinc content can lead to deposit formation on your valves, and spark plug fouling" (Rau).

If zinc-d is so good for your vehicle, why haven't oil manufacturers been putting more of it in their standard mix of oil and additives? Actually, oil companies have been decreasing the amount of zinc-d because the evidence indicates that zinc-d causes deterioration of catalytic converters.

The bottom line is that outside of the testimonials of happy and satisfied customers and the guarantees of company executives about the wonderful effects that studies have shown will follow the use of their products, there isn't much support for using oil additives. Of course, there are those millions of customers who buy the stuff: aren't they proof that these things really work? Not really. They're proof that this stuff really sells!

cleansed, not coated

On the other side of the engine block are those additives which will cleanse your engine, not coat it. Stuff like Bardahl, Rislone and Marvel Mystery Oil claim they can make your engine run quieter and smoother, and reduce oil burning. These are products which contain solvents or detergents such as kerosene, naphthalene, xylene, acetone or isopropanol. If used properly, I suppose these products will strip off your Teflon and zinc protective coatings! But unless you have a really old and abused car, you probably have no need of stripping away sludge and deposits from your engine. Thus, you probably have no need for these wonder cleaners. If you overuse such products you can damage your engine by promoting metal to metal contact.

If you use a synthetic oil, such as Mobil 1, you are advised not to use any engine treatments or additives. Mobil claims that

The use of an engine oil additive is not recommended, either by Mobil or by virtually any vehicle manufacturer. In fact, it may void your new-car warranty.

Finally, you may have seen the commercial where two engines are allowed to run without any oil in them and the one which had the special oil additive keeps on ticking after the other engine has conked out. This may be appealing to the car owner who never changes his or her oil or who runs his or her car without oil, but it should be of little interest to the person who knows how to take care of their automobile.

Should you invest in something like Tufoil? It is touted as being "a super-suspension of micro-miniature PTFE particles and soluble Molybdenum, permanently suspended in oil." And, it will not clog filters or oil openings, according to the manufacturer. Or, how about Lubrilon, which contain a nylon polymer that will coat your metal parts? Or Bishop's Original Permafused Lubrication™, which also coats your metal parts with an anti-wear lubricant film? It's your money, but I think you'd be better off if you just changed your oil and oil filter regularly. And don't forget to change the fuel and air filters at the recommended intervals. We can't say for sure that these new products do no good, but what good they might do is probably not necessary or of much value for the average vehicle owner who takes proper care of the vehicle.

reader comments

further reading

"Snake Oil! Is That Additive Really A Negative?" Fred Rau, Road Rider,August 1992.

The Not-So-Clever Oil Additives


Agreement Safeguards $10 Million in Redress to Consumers July 23, 1997 FTC press release

Last updated 29-Oct-2015

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