Tech Tip #184: How to Break-In a Remanufactured Deutz Engine

Dr. Diesel
Written by Dr. Diesel

How to Break-In a Re-manufactured Deutz Engine


The lube oil you choose to run in your Diesel engine plays a vital role in the ability of the engine to operate safely, achieve a long life, and have a minimal impact on the environment. Considering today’s modern engines, the lube oil has to meet some very exacting standards to achieve those goals.

In general, diesel engine oil must meet the following requirements:

  1. Retain sufficient viscosity at all operating temperatures to assure a lube oil film between mating parts.
  2. Remain stable at all variable engine operating temperatures.
  3. Perform cleaning and cooling functions.
  4. Prevent corrosion.

API Classification

In order to meet these requirements successfully, it is imperative that the correct lube oil classification is met. The American Petroleum Institute works with engine manufacturers and oil suppliers to establish classifications criteria suitable to meet those demands.

SAE Grade (Society of Automotive Engineers)

Equally important is the SAE grade of the engine oil that is used. The SAE grade selected should be chosen based on the highest ambient temperature at the engine operating site. If the lube oil grade used is to thin oil will pass by the piston rings into the combustion space.  Lube oil API Classification and SAE Grade requirements can be found in the engine operators’ manual and should be adhered to.

Oil Consumption

During engine operation, some lube oil will be consumed. Lube oil provides a seal between the piston rings and the cylinder wall and during the combustion process, some of the “sealing oil” will burn and travel out the exhaust valve. The amount of oil burnt during the process is influenced by several factors, but will generally fall in a range of from 0.3% to 0.5% of overall fuel consumption. (In cases of continuous low power demand, as high as 0.7% may be normal)


Due primarily to more exacting machining tolerances and more stringent quality measures, modern diesel engines require less “break-in” than their predecessors did. Most engines however, will experience higher than normal lube oil consumption during the initial period of operation, which depending on the load factor applied, should stabilize within the first 150 to 200 hours of operation. During this time, the pistons rings are “seating”, or forming a perfect seal with the minute variances that exist between the rings and the cylinder wall. It’s important to understand that this process is greatly influences by the load applied to the engine during its early life and as long as the engine is demonstrating a decrease in oil consumption, this means that the “break-in” period is still occurring and more time (hours of operation) may be necessary.

Extended Periods of Low Load

Engines subject to extended periods of low loads (or prolonged periods of idling) will at the very least take longer to seat the piston rings, and extreme cases, may not do so at all. Low loads or extended idling will cause incomplete combustion and the formation of a carbon compound which will essentially fill the crosshatch shaped grooves that are applied to the cylinder wall. When the occurs, the cylinder surfaces develop a “mirror finish” becoming “Glazed”, causing oil pumping past the rings up into the combustion chamber where the oil will partially burn and be pushed out into the exhaust system. The liquid oil passing into the exhaust system can result in leakage at the exhaust manifold gaskets and “wet stacking”. The carbon compound that forms the glaze on the cylinder wall is very hard, but is caught early applying full load on the engine on the engine may correct the condition. Otherwise, the cylinders will need to be “de-glazed” with a honing tool and the piston rings replaced. Of course after replacing the piston rings the “break-in” period will start over again.


Select the correct oil by consulting the operator’s manual. When the engine is new, try to limit the idle time of the engine by shutting the engine down when the machine is not in use. It’s best to apply a heavy load to the engine during the “break-in period” in order to seat the rings as quickly as possible. Sufficient load will assure a rapid “break-in” period and good piston ring sealing.

Lube oil consumption is expressed as a percentage of the fuel consumption during a test period of about one day. The calculate consumption, top off both lube oil in the engine and fuel in the tank. Then operate the engine for a full work day and measure the exact amount of lube oil and fuel necessary to bring both back to the “full” level.

Oil Consumption % = Quarts of lube oil added / Gallons of fuel used X 4

Dr. Diesel
Written by Dr. Diesel
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