Are oil and fuel additives good for your engine?

Yes

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by Admin Tronthor

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Although there are as many opinions as there are additives, the blanket statement that adding something extra to your fuel or oil is bad for your engine is patently false. Additives which actually do what they claim will be beneficial to your engine life and performance throughout that life, and will extend the useful life of the engine while reducing the number of repairs required.

In order to realize these benefits a few things have to be taken into consideration. The first of these is the "snake oil test". In short, if it sounds too good to be true, it probably is. I am not aware of any rules other than the basic advertising laws that apply to claims made about such additives. I have seen many products which claim that you only need to add them to your engine oil once every 25,000 miles...or even longer intervals, and for this you will see all sorts of benefits. Considering that even with the best of care the average passenger car engine is going to require that the piston rings be replaced someplace around 200,000 miles, adding something to the oil every 25,000 is not going to do much.

So, does this prove that additives are bad? No. There are additives which have been shown to provide benefit. Additives such as those containing PTFE (Teflon) micro beads which are then forced into the pours of the metal on wearing surfaces. These additives, the ones that work, will indicate on the packages that they must be added with EVERY oil change, and they do NOT have any claims or recommendations that you can extend the length of your oil change interval as a result of using the product. One such product was Tuffoil(tm) which was produced by Dupont. This product was even approved by the FAA for use in aircraft piston engines. In order to gain this certification, multiple engines are run under maximum power output (imagine driving your car with a full load of passengers and cargo in it, on the highway at a speed that put you at the top of the power curve the entire time) for a 2,000 hour period (this equates to 130,000 miles at 65 mph) without stopping. They place the engines on a test rig that allows the effect of an oil / fluids change at a recommended interval without shutting down the engine. Do you think that you car could do that? I wouldn't want to put one to the test. To gain certification, the additives must show that they do not cause a failure in the engine that is statistically earlier than the engine being run with only the recommended (by the manufacturer) lubricants, coolants, etc.

What does a PTFE additive do? Primarily it will reduce friction. Most importantly it will reduce friction at startup when normal oil pressure has not been established but parts are moving. A critical set of parts are the crank shaft, connecting rods, wrist pins, piston rings, cam shaft, cam followers, push rods, etc. In short all the moving parts inside the engine. Many of these have no bearings other than a thin film of oil under pressure to allow them to move. This is where these types of additives will gain you some benefit.

Other additives will provide additional cleaning or lubrication functions in the extreme areas of the engine. A classic example are the valve guides. In particular the exhaust valve. Exhaust Gas Temp (EGT) can be as high as 1,000 degrees F. This is in conditions of high power output, idle temps would be much lower. If you have ever seen the turbochargers on high performance engines after a long run, you will note that they are glowing red hot - 900+ degrees F. We are talking about a very harsh environment. The exhaust valve guide has a relatively small amount of metal involved due to its location and the need to maintain a certain volume of open space for the exhaust to go through while being tucked into a cramped space. This part is both lubricated and cooled by the engine oil. As you can imagine there is some burning of the oil involved here as well as some sorts of chemical breakdown of the oil. It is in this sort of extreme location that an additive containing Tricresyl Phosphate (TCP) will help you. Although already an additive in the formulation of both lubricants and fuels it is hard to tell how much has been added to your particular engine oil or brand of fuel. One place where this lubricant will benefit you is in lubricating the exhaust valve guides. So what? Well, go and see what the price of a valve job is for your car and you will know "what". Ware of the valve guides, both intake and exhaust will lead to oil consumption and increased emissions as well as increased build up of soot and other byproducts of burning lubrication oil in your engine on the valves as well as possibly clogging your catalytic converter(s). An excellent and readily available of TCP is the classic Marvel Mystery Oil (tm) additive. In the past I have added this to a running engine with "hanging" valves and you can actually hear the engine idle smooth out.

Having beat the lubrication side to death, we move to fuel additives. The same rule of thumb applies: If it seems too good to be true, it probably is. There is a basic fuel economy that you are going to get from any given engine based on its own efficiencies which are based on its design. Fuel contains a certain amount of energy - BTUs per gallon - based on its formulation. The move toward high % ethanol mixtures means that we are seeing lower BTU/gallon numbers in the tank. Your car will get lower mileage on E-85 than it will on straight "dinojuice". There is nothing that you can do about that. The trade off is cleaner combustion. So, what are fuel additives good for anyway? Again, the reason for adding things to your fuel mirrors that of the engine oil - preserving the machine and allowing it to perform as advertised, or perhaps a little better, by reducing the build up of performance robbing "sludge". Here again we turn to TCP. In the fuel system this provides both a lubrication function, which is welcome to those hard working items like your fuel pump - generally a small electric motor located inside your fuel tank that runs a pump trying to maintain approximately 30 PSI while delivering that gallon of fuel that you use every 10 - 60 miles of travel to you go depending on the car your are driving and how you are driving it. TCP is again a wonderful thing to have in your tank. Not only will it lend a hand in lubricating, and thus prolonging the life of, your fuel pump, but it will help to clean your injectors, fuel pressure regulator(s), compression ring on your pistons, valve seats (where the valves and the engine meet to form a tight seal, and possibly even help keep the catalytic converter clean and happy (I have no evidence of this other than never having had one fail while using TCP additives in the fuel)

So, in summary, while "snake oil" additives are generally agreed to be bad, and potentially damaging to your engine and fuel system, there are a small number of additives that will not only improve the performance of your normal lubricants and fuels - provided that you follow recommended procedures provided by manufacturers, but will also prolong the service life of your engine. With the cost of repairs and replacement being high, this is the goal that we want to reach: A clean as possible running car that continues to run as long as possible.

As a side note, I generally see my cars and trucks exceeding 200,00 miles with nothing more than regular maintenance: oil and filter changes, "tune ups", timing belts at recommended intervals, a fuel pump around 150,000 miles (they just don't last forever). At that point usually 8-15 years depending on the driving, the body usually gives up - New England is not known for being overly kind to metal boxes on the roads. I use Marvel Mystery Oil (tm) in both the fuel and oil, and also add a PTFE based oil additive, formerly Tuffoil(tm) but supply has become problematic and I am looking for a substitute and currently using "MPT" (tm) which seems to have a very similar formulation. Since switching to 100% synthetic engine oil and employing PTFE and TCP additives in the '80's I have not had to perform a valve job on any engine due to a loss of compression due to valve burn or ware. the cumulative experience on which this opinion is based comes from about 2 million odometer miles across our "fleet" in addition to non-automotive applications in both diesel and gasoline applications.

Happy Motoring.

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