Do You Need to Prelube Your Engine Installation?

It is widely understood that the period of time between when the engine begins to turn at startup and the time when fresh oil from the sump reaches moving parts causes up to 90% of the wear an engine sees during its lifetime. A prelube pump puts the oil where it is needed before the engine begins to move, thus reducing this high wear period.

Historically operators of large engines would avoid shutting them down. This was done to reduce startup engine wear in addition to other operational advantages. In colder climates for instance, letting an engine cool all the way down can cause significant problems when trying to restart it. Fuel “gels” and very cold engines can be nearly impossible to start. Until recent years the simplest and most widely used solution to this problem was to just leave the engine running. Large engines might only be shut down for periodic maintenance. Fuel was inexpensive and environmental concerns were not considered. As the price of fuel climbs ever higher and idle emissions are no longer acceptable, operators are shutting down engines more than ever before.

Fuel costs as well as the EPA and other regulatory agencies are increasingly requiring engines to go into “auto start” mode rather than just idle. In auto start mode the engine starts its self and runes only long enough to warm the fuel, coolant, oil and the engine block back up to operating temperatures. The engine then shut itself back down to save fuel and emissions. As a result the number of times some engines need to be started in their lifetime may go up from only 80 or 100 to as many as 86,000 times. It’s easy to see how wear rates that were considered acceptable with only 80 lifetime starts would have a significant impact on engine life with 86,000 lifetime starts.

In the end the decision as to whether a prelube system is appropriate for a given installation comes down to the cost benefit analysis of three factors. The number of times the engine will need to be started in its lifetime, and the cost of replacing/rebuilding the engine, against the cost of adding the prelube system.

As an example a good prelube system may run in the range of $1500 by the time it is installed. So if the engine is small and only costs $10,000 a prelube may be impractical. As the engine size goes up in the calculation though, a $1500 investment could save many times its price in future repairs and downtime. Likewise if an engine were only going to be shut down every three months for maintenance, the cost of a prelube system might be unjustified but for a system that is restarted multiple times a day it would be a necessity.