Under the Hood

Last month I talked about motor oil and all its slippery details. This month: a critical look at oil additives. You’ve probably heard dire warnings that when you start your engine you’re grinding metal on metal, resulting in about 85% of total engine wear.

First, this kind of wear isn’t responsible for engine failures. Second, bearings aren’t running dry--oil remains after you’ve turned off the engine. Finally, the wear that’s taking place has far less to do with metal-to-metal contact from lack of oil than with byproducts of combustion. Those acidic gases condense and etch cylinder walls and piston rings. Once oil pressure comes up, which happens quickly in a healthy motor, the problem is taken care of. That’s part of the reason it’s a good idea to run a cold engine 15 to 30 seconds before driving off.

It’s this kind of wear that PTFE (better known as Teflon) additive makers used to claim their products would prevent. However, because PTFE (polytetrafluoroethylene) doesn’t bind with metal parts, this kind of wear isn’t prevented by the additive.

As I’ve said before, oil already has its own additives, and nobody aside from the additive makers recommends putting more of anything into your engine.

The base for most additives is 50-weight engine oil. To the base, the company might add PTFE, zinc dialkyldithiophosphate or varying combinations and amounts of what’s already in oil. There are also products that are made up primarily of solvents and/or detergents.

PTFE is a popular ingredient for oil additives, and the brands that contain it are among the bestsellers, including the No. 1 additive, Slick 50. Despite its popularity, PTFE is by no means a proven ingredient for use as an engine lubricant. DuPont’s fluoropolymers division originally took the stand that PTFE was not useful in internal combustion engines. DuPont went so far as to refuse to sell PTFE to any company that was planning to use it that way. It was sued for restraint of trade and lost. Additive makers also found other sources for the product. DuPont’s official stance is now much more neutral. The company has said it has no proof of additive makers’ claims and it has no knowledge of any advantage gained from using PTFE in engine oil.

Were that not enough, in July 1996, the Federal Trade Commission accused Quaker State, the maker of Slick 50, of false advertising for making unsubstantiated claims about the additive’s ability to reduce wear, cut emissions, increase mileage and boost horsepower. Quaker State and its subsidiaries signed a consent agreement limiting their advertising claims in July of last year. (Keep in mind that a consent agreement is for settling the complaint filed by the FTC and does not constitute an admission of wrongdoing.)

But what’s really wrong with PTFE in engine oil?

In a word, it’s solid. Sure, it’s a very fine powder, but a solid nonetheless. And if PTFE is capable of binding to metal parts under extremes of temperature and pressure, then it’s probably really good at collecting in places where temperature and pressure are lower, such as oil passageways. Tests performed by NASA’s Lewis Research Center found that PTFE provided no benefit for bearing surfaces. The study also found that in some cases the solid tended to accumulate at inlets, blocking the flow of oil and depriving parts of lubrication.

Another point to keep in mind is that your oil filter’s purpose is to take suspended solids out of the oil. Too many solids will clog your filter and cut pressure in the engine. Some additive makers say they use a PTFE that’s fine enough for the particles to pass through an oil filter. However, PTFE expands when exposed to heat.

A test by the University of Utah Engineering Experiment Station involving a PTFE additive detected a pressure drop that resulted from possible clogging of the filter. “In addition,” the report read, “oil analysis showed that iron contamination doubled after using the treatment, indicating that engine wear didn’t go down--it appeared to shoot up.”

This test was paid for by Petrolon, the marketers of Slick 50 at the time. It wasn’t all bad news; there were some increases in horsepower (5.3% to 8.1%) and mileage (11.8% under a light load and 3.8% under a heavy load). Are those increases worth lower oil pressure and increased wear? I don’t think so--there are other ways to get those benefits without the negative effects.

So while it sounds good to coat your engine’s parts with Teflon, it doesn’t mean the reduction of friction is going to be as effective as a nonstick omelet pan.

Another popular active ingredient in oil additives is zinc phosphate compound. It’s not the stuff in cold lozenges but a chemical that is already in motor oil in varying amounts. There are higher amounts of zinc in performance or racing oils because it offers protection against metal-to-metal contact, particularly between cylinder walls and piston rings.

That kind of contact shouldn’t occur except under the most extreme conditions, such as racing or shifting at redline all day long. But more zinc doesn’t provide more protection, according to the research; it prolongs the protection. In addition, high zinc levels can cause valve deposits and foul sparkplugs. A few years ago, oil companies voluntarily cut the proportion of zinc in their products because research found that the compound was deteriorating catalytic converters prematurely.

If you run your car very, very hard or have something old enough to be lacking a cat converter, higher zinc content won’t be a big deal. But why pay extra for something you can get by purchasing a higher grade of motor oil?

Less “modern” or “advanced” additives consist of 50-weight oil and some combination of what is already in engine oil. The difference is that the additive’s manufacturer has increased the concentration of one or more of these compounds.

But more is not necessarily better.

Oil companies formulate their product with a package of additives that has been derived from research. Expensive research. They then submit these formulas for certification. Would they submit something to auto manufacturers that wouldn’t meet the standards? Not after shelling out big money to a bunch of folks in white lab coats who get their thrills mixing and matching chemicals.

Sure, more of something might not cause harm, but why tinker with the balance you’ve already paid for by picking a good brand of oil? Save that money for more frequent oil changes.

On to the old-time oil additives, the ones your parents or grandparents might have used. These are mostly made up of solvents and detergents. Again, most motor oil contains some solvents and detergents, but not in quantities approaching the additives. One well-known product is more than 80% kerosene. The idea is to rid your engine of sludge and carbon. But how much is too much? That’s going to be almost impossible to tell, and solvent use risks reducing the oil’s ability to lubricate.

If you feel your engine needs this kind of treatment, you would probably be better off using a flushing oil. This stuff is very lightweight (read: Do not drive with it in the engine!) and expensive. Drain the oil, keeping the old filter. Fill it with the flushing oil, and run the engine at fast idle for 20 minutes.

Turn off the engine, drain the flushing oil, change the filter and fill the crankcase with the good stuff. Beyond that, there’s a limit to how much elixir will really clean out your engine. More frequent oil changes will prevent the need for this kind of potion and won’t risk harm like the solvent additives will.

What additive then, if any, should you use? None. Testing by major independent labs and engine manufacturers shows that these products are ineffective at best and, in some cases, do more harm than good. No car maker recommends oil additives, and neither do the oil companies that don’t market one.

Q & A

Have you got any advice for me on a problem I am having understanding octane level? My Toyota dealer told me that I should only use the highest octane available in my 1970 Land Cruiser. It has a straight-6 Toyota F-series engine with no modifications. The engine (a replacement from Japan) has about 70,000 miles on it. I thought that these engines could be used anywhere in the world and could use just about any gasoline available (read: low octane), but the dealer tells me it should only use the highest-octane fuel. The engine has burned through three sets of valves (all repaired at my expense at the same dealership) in the last six months, and they claim that it is burning too hot using 87 octane. The last set that burned through caused one of the valve stems to shatter the top of the piston, score the cylinder and bend the crankshaft at a cost to me of $2,800 to fix it. I cannot afford to keep replacing these valves. Should I ditch the dealership, the engine or the 87 octane?

LINDSEY PHILPOTT, Via the Internet

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As you might suspect, this doesn’t lend itself to an easy answer. The engine’s ability to run on a particular fuel depends on a couple of things, with compression ratio being the most critical. The higher the ratio, the higher the octane. Other factors include how hot it is where you’re driving and how hot the engine runs. I’m a little puzzled that the dealer says the lower octane is making the engine run “hot.” Perhaps that’s his simple way of saying you’ve got pre-ignition detonation. Does the engine ping or knock when you use 87-octane fuel? There is a condition known as inaudible detonation, but the valve consumption of this engine sounds like it should have pretty obvious symptoms.

I’d say run it on at least 89, make sure it’s tuned to factory specs, make sure the coolant system is up doing its job. Last, but not least, make sure your valve rockers are set properly; too tight and your valves will get thrashed. I called Cool Cruisers, a Dallas-area restorer of early Land Cruisers, and a representative said the company tells its customers to use 89-octane fuel. He also agrees that something more than octane is causing the valve failure. If this dealer can’t offer some kind of satisfaction and won’t warranty at least the parts for a year, find a good, independent shop that has experience with the old Cruisers. Finally, a bent crank? I’d go shopping for another engine.

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I read in the paper that you rebuilt an old air-cooled VW engine. A fellow is rebuilding the engine in my Karmann Ghia after 190,000 miles. In order to give it more oomph for entering freeways and escaping runaway big rigs bearing down on me without brakes on a downhill run, the engine is going to be built for a little more performance than a stock engine.

The individual who is rebuilding my engine is accustomed to off-road vehicles. He would like to put headers on the thing but is concerned about two issues: weight and clearance. He wants the setup to last. He also wants me to research this issue. Kind of like the blind leading the blind. Is there an issue with hanging this kind of weight off the engine? Do people build supports for this type of exhaust?

HUDSON LEGRAND, Via the Internet

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Here’s what I would have done way back when, had I not been a starving student. First, make sure the engine cases are in good shape--you might want to bore the crank seats to make sure they’re all straight and the same diameter. Next, for more power, add more displacement. You might not want to go too big on that end, perhaps 1,750 cubic centimeters, so that it will still drive with good manners.

To make sure that power is handled smoothly, invest in a counterbalanced crankshaft. I would probably go with stock cams, electronic ignition, dual Webers, oil cooler and a performance exhaust--a.k.a. a header. You should be able to find a quality unit that fits with no more than minimal heat shield or body cutting, if any.

Weight should not be a problem with a well-designed exhaust. If your budget’s big enough, you could spring for a lightened flywheel and a performance clutch. The former will do more for off-the-line performance; the latter will ensure that power is efficiently transferred to the wheels. And if you really want to soup the thing up, go with a supercharger. Keep in mind, however, that the normally aspirated, i.e., not supercharged, engine is probably going to take you from about 75 to 80 horsepower to 100 to 110. That might not make your Ghia a screamer, but it should be quicker to 65 mph.