What Oil Should I Use To Break-In My Rebuilt or New Deutz Or Perkins Engine?
In the new age of diesel and gasoline engine rebuilding, one thing has not changed much in the final step of building your engine, the break in. It is that gut-wrenching feeling of the first start (and several after) when all your hard work comes together and gives life to a mechanical marvel. This is a very important period for your engine and just like the assembly lube you used during your rebuild, the first oil your engine sees is equally important. This tip is to help you make the decision of what oil is best for your break in.
Not all oils are made equally and there is a lot of confusion about what to use. First off, always use the oil weight recommended by the manufacturer for the conditions and environment you are operating in. Too light of an oil can cause failure in lubrication due to thinning and too heavy weight can cause lack of lubrication if your oil pump can’t move it easily enough. We have seen heavy weight oil cause friction in main and rod bearings due to surface tension created by the wrong oil.
Next is the choice between Conventional and Synthetic; certainly an ancient debate. Many people have strong opinions related to too much or too little lubrication, additives, or even “Just because”. In reality, it has little to do with any one of those “explanations” and more as all of them as a whole.
Lubrication is very important when it comes to “breaking in” your engine, but the first start up needs a specific type of lubrication. We have all heard the term “seating the piston rings”, this is where there right lubrication comes into play for your break-in oil. When the engine is being built it is common for the cylinder walls to be “honed”. This process causes little grooves in the cylinder wall that help oil to cling to the cylinder walls to maximize lubrication. These little grooves have microscopic peaks and valleys which hold oil in between them. Fresh honed cylinder walls do a great job at holding oil; too great of job. This is where break in oil comes into play. It allows for proper lubrication of the high load areas such as the main and rod bearings, camshaft and tappets, while simultaneously providing controlled friction in low load areas like the cylinder walls. The proper lubrication balance helps the piston rings to wear down the peaks of the hone pattern in a controlled environment. By taking down those peaks, the area for oil to cling to is reduced, not so much that the piston is not lubricated but so there is less excess oil on the cylinder wall. If excess oil is held on the cylinder wall, excess oil can be consumed by the engine while running, which if allowed to continue over time can cause a slew of problems down the line. This is one of the reasons we recommend using conventional oil versus synthetic oil. Conventional oil and synthetic oil are similar in may ways, but conventional oil generally has less molecular uniformity (i.e. molecules vary more in size and shape while synthetic oil molecules are more uniform) than synthetic. Synthetic oil’s greater molecular uniformity is what helps to make it superior for allowing engines to run for a longer extended life. The lack of uniformity in conventional oils is what helps when breaking in an engine to allow for the type of friction desired in the initial break-in period. In short synthetic oils are just too “slick” to allow for the proper wear for engine components during break in.
Let’s move on to additives. These days there is a smorgasbord of different chemicals additives intended to help with all sorts of things. They help with things like keeping components clean, increasing the shear stability (i.e. helping prevent oil from thinning) , and maintaining the ability and ease of the oil to flow in low temperature environments. Clearly we can understand why you might want these additives, but not all of them are helpful for your engine during break-in . During break-in, we think that two of the more important additives are ZDDPs (Zinc Dialkyldithiophosphate) and Molybdenum Disulfate.
ZDDPs contain organometallic compounds that have high anti-wear and anticorrosion properties when in the right environment. They help to create a protective film on engine components by decomposing to form “tribofilms” on high pressure and high temperature components. These are sacrificial and allow for lubrication in the event of short-term oil loss, (cranking, cold start, etc.) as well as just being a protective layer during normal engine operation. The downside of running oils with high levels of ZDDPs is that they can cause issues with catalytic converters or DOCs (Diesel Oxidation Catalysts) if used for prolonged periods.
Molybdenum Disulfate is an inorganic solid compound dissolved in oil that is known for its stability at high temperature and its high-pressure resistance (350C to 1,100C & +250,000psi). It creates layers on the metal surfaces of the engine helping to reduce friction during cold starts to smooth imperfections in bearing surfaces, which help reduce friction and act as kind of a sacrificial layer during brief periods of low lubrication/more metal-on-metal contact.
Finally, we get to the question of “What oil do I use?”. The best answer I can give you is, do some research. With any insights gained above, pick the oil that best works for your application and environment your engine is operating in. Some engines might need a 5W-30 oil while others a 15W-30 and not all brands make all weights of oil. In our experience, we have found that Rotella T4 is a great reasonably priced option that has an almost 35% increase in Zinc from the next runner up on the list I found while doing some research for this tip. There are also oils out there that boast over 300% of what Rotella has in Zinc but those can often be quite expensive, and the recommended values and oil compositions in the market seem to change all the time making it hard to keep up on the latest. In the end, the choice is yours, but we hope with we have helped to allow you to make an educated choice and not just take shot in the dark. We hope you enjoy the fruits of all the effort you put into your new engine and we are here if we can help.
Of course, there is more to breaking in your engine than just your oil selection. For additional information see How To Break In A Rebuilt Engine and Foley Tech Tip #184: How To Break-In A Remanufactured Deutz Or Perkins Engine.
Always refer to the engine manufacturers oil and break-in recommendations.
