Why Does My Car Leak Oil After an Oil Change Service?
Today’s question comes from Dave S. in Grand Rapids, MI. Dave asks:
“After getting a standard lube, oil and filter service for my 2005 Nissan Altima at my neighborhood quick lube, I noticed spots of oil on my garage floor. This was definitely not occurring before I got the oil changed. I took it back the next day and they verified that the drain plug and filter were properly installed. They said it might be leaking oil but couldn’t tell from where. What should I do now?”
When the oil and filter in your car or truck are serviced properly, this in and of itself will not cause your vehicle to leak oil. That said, it is possible that changing the oil can make an existing leak more prevalent.
There are several places on an engine that oil can leak from. Cylinder heads, valve covers, oil pans and crankshaft seals and gaskets are among the most common oil leaks we can encounter. Gaskets are usually made from rubber, plastic or cork materials (or some combination thereof), and it’s not uncommon for these parts to begin to leak over time due to the heat, pressure and other elements that they are consistently exposed to. Vehicles that are more than a few years old, and have accumulated some miles on the odometer are more prone to the occasional oil seepage. It’s just one of the tradeoffs of owning an older car or truck.
The reason that changing the oil can make an existing oil leak worse is the fact that old, dirty oil is thicker than clean fresh oil. This is commonly referred to as ‘viscosity‘. Simply put, thinner motor oil will leak faster than thicker oil, so any existing oil leaks may become more noticeable. This is not to imply that changing the oil caused the oil leak – the problem was already present.
So what should you do if you notice an oil leak?
Due to the compact nature of most engine compartments, it’s difficult to simply open the hood of your car or truck and immediately be able to identify accurately where an oil leak may be coming from. The best course of action is to bring the vehicle to a reputable repair shop for proper diagnosis.
The diagnostics process usually consists of cleaning the residual oil from the outside of the engine with a degreaser product. From there, the oil is refilled to the proper level and a dye is added to the oil. After that, the engine is started and allowed to run for a little while to allow the dye to circulate throughout the oil.
The time it will take to diagnose the problem depends on the severity of the leak. If the leak is bad, it should show up right away under a UV light. If the leak is more subtle, the vehicle may need to be driven for a day or two (or longer) before the leak is detectable. In any event, once the source of the oil leak is correctly identified, a repair can be properly performed to replace the faulty part. Finally, more dye is added to the oil and it is advisable to return to the shop for a final check, to make sure that no more leaks exist.
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