Curbside Clueless: Additives: Snake Oil or Magic Elixir? Part 3a Crankcase Additives

Well we’ve discussed fuel and coolant additives in part 1 and part 2 so now it’s time for crankcase additives.

For those faithful readers who have been waiting for this for awhile I apologize for the delay. I had hoped to get this done before the start of the FRC Robotics season. Unfortunately one of the reasons I gladly accepted this opportunity was to get experience as a “professional” blogger and transfer that knowledge to my Team’s website.  In addition to getting that up and running I masterminded a Facebook contest to promote our page and thus website among the FIRST community at the annual kick-off event. Due to snowfall Mon and Tue and projected heavy snowfall for today we did not end up building Wed so I was able to finally concentrate on this. Now  back to your regularly scheduled programing.

Engine oil additives are most likely the most commonly found miracle worker in a can on auto parts store shelves. Like the others they come in a number of basic flavors. Most of them can be broken down in to two main categories.

Many fall under the “cleaner” category, and the are supposed to improve operation by cleaning the engine, freeing sticky rings, valves and lifters, and sometimes stop oil consumption due to leakage. Most of the products that are sold in this segment rely on some sort of solvent similar to the fuel system cleaners, in fact products like Marvel Mystery oil and Sea Foam state it is great for use in your crankcase just as well as your fuel tank. Yes solvents will clean the inside of your engine, as the name implies this products work by dissolving the oil sludge and gum. The problem is that a solvent isn’t selective in what it acts on so it will attack the engine oil too possibly lowering it’s viscosity. This can be a bad thing as the oil may not be able to have enough film strength to prevent wear. Because of this some products such as Sea Foam state that it should mainly be used as a pre oil change flush and if you are going to install in with fresh oil that you should monitor the oil closely and you may need to change it earlier than “normal”.

What if you pop the valve cover of your newly aquired Curbside Classic and it looks like this.

You might be tempted to use an Engine flush product.

These products sold specifically as flushes often instruct the user to only run the engine at idle and then just for a few minutes. These can be quite dangerous to your engine. Not only does the large volume of solvent degrade the oil significantly, on a very dirty engine with a lot of thick deposits it can break free a ton of big chunks. Those chunks can often plug an oil pump pickup screen solid completely starving the engine of oil. Those that aren’t large enough to be trapped by the screen must travel through the oil pump before they can be removed by the filter. If the filter is already partially plugged it may open the bypass valve either somewhere in the engine itself or the filter, and it won’t be filtered out. Either way freeing those deposits that weren’t on areas that are lubrication points and making it circulate to those points where the oil does serve as a lubricant and possibly plugging things like lifter passages and squirt holes is not a good idea.

Many that claim to stop seal leaks by “conditioning” the seals actually use solvents that purposely aren’t compatible with the common materials used to make shaft seals and gaskets. These are often referred to as seal swellers because they are actually absorbed by said seal causing them to swell. In the process of swelling rubber seals in particular get much softer which may allow them to conform to the shaft better, for a while. The fact is these products reduce the strength of the rubber and it will wear quicker as well as be easier to tear.

The next big group of crankcase additives are what I’ll call fortifiers. Most of these are either a high viscosity base oil or include friction modifiers to improve its hot viscosity performance. They usually claim the following benefits, quieter running engine, reduced oil consumption due to both leakage and burning, better oil pressure, or improving performance and MPG by increasing compression. They also often claim that engine wear, often specifically start up wear is reduced. Many of those claims are true to some extent or another. Thicker oil will usually result in a higher oil pressure reading than a thinner oil when you are operating below the pressure relief valve setting. It may also quiet or hide knocks and clatter by providing a better “cushion” of oil. Thicker oil also is less likely to leak past worn seals and valve guides. Higher viscosity may even provide a slight increase in compression and reduction in blow by due to its higher film strength providing a better seal for the rings. Due to the increase in thickness they may also slow down the natural affect of gravity draining the oil out of the passages which could reduce start up wear. On the other hand that thicker oil will take longer to build full oil pressure and reach the end of the lubrication system thus increasing wear. Thicker oils can also cause a form of oil starvation on engines that operate at high rpms. The oil is sheared rather than flowing when the speed of the surfaces exceeds the flow rate of the oil. So if you have a engine with low oil pressure, leaky seals, guides or rings these may provide some benefits but of course they will not repair parts that are worn.

Because of the sheer number of types and brands of crankcase additives you’ll have to stay tuned for part 3b, hopefully in the not to distant future, when we will discuss some of the best known, most controversial and litigated crankcase additives.

As always send your questions to, as I do need a break from Robotics now and again and frankly answering questions is easier for me than composing an article from scratch.