Thursday, January 1, 2026

What is the main weakness of a Subaru 2017 PZEV engine: The Oil Seals and Gaskets. Why? (Part 2)

NOTE: I just found out that this is something that commonly happens to boxer engines in Subarus that are non-Turbo where the Engine Seals degrade by 60,000 to 100,000 miles and need to be replaced. We just paid $3600 to do this during Christmas for my daughter's car. One of the causes of this might be not changing our synthetic oil every 3 months and possibly not warming your car up enough when you start it?

Not sure about all this because every driver is individual and everyone lives different places and drives their cars differently. However, it might be important to prepare potentially for a $3600 bill to change the oils seals and gaskets if your Subaru Boxer engine is between 60,000 and 100,000 miles on your odometer. 

end note. 

I realized that I could ask what I really want to know now which is: "How do Subaru Dealerships remove and engine to replace oil seal and gaskets if they go bad from the synthetic motor oils?" 

by the way in the process of this this is the specific plan for removing  a "Boxer Engine" in a Subaru to replace the Oil Seals and Oil Gaskets:

 
 

How do Subaru Dealerships remove and engine to replace oil seal and gaskets if they go bad from the synthetic motor oils?
Thinking
Searching
Subaru dealerships typically
remove the engine from the top of the engine bay to replace leaking oil seals and gaskets, a process that can take between 2 to 4 hours for skilled technicians. While synthetic oils are standard for modern Subarus, leaks often stem from the gradual degradation of RTV sealant or older black rubber seals that shrink or harden over time. 
Engine Removal Process
Dealership technicians follow a standard sequence to pull the engine for major reseals, such as cam carrier or rear main seal replacements: 
  1. Fluid Drainage: Oil and coolant are drained first.
  2. Top-Side Disconnection: Technicians remove the intake manifold, battery, and alternator. Accessories like the A/C compressor and power steering pump are often moved aside without disconnecting their lines to avoid recharging the systems.
  3. Bottom-Side Disconnection: The exhaust manifold and downpipe are detached.
  4. Driveline Separation: Bolts connecting the engine to the transmission (bell housing) are removed. For automatic transmissions, the torque converter must be unbolted from the flexplate through an inspection hole.
  5. Lifting: Using an engine hoist, the motor is lifted straight up and out. This is easier on Subarus because the transmission remains in the car and the engine harness usually disconnects via one or two main plugs. 

Common Seal and Gasket Replacements 
Once the engine is out or "slid forward," technicians address specific leak points:
  • Cam Carriers: A common leak point on newer non-turbo motors (60k–100k miles); the engine must be pulled to reseal these with fresh RTV.
  • Rear Main Seal: Located where the engine meets the transmission. Technicians often use a self-tapping screw or specialized tool to pull the old seal out before pressing a new one in flush with the block.
  • Oil Pan: While some oil pan leaks can be fixed by jacking the engine up an inch for clearance, many dealerships prefer pulling the engine entirely to ensure a clean mating surface for the RTV sealant.
  • Oil Separator Plate: Frequently replaced alongside the rear main seal; older plastic plates are upgraded to metal versions to prevent future leaks. 

Impact of Synthetic Oil
While modern 0W-20 synthetic oil is required for Subaru engines, it is highly "slippery" and can more easily seep through seals that have begun to fail due to thermal cycling or age. Dealerships now use improved brown rubber seals and specific sealants (like Fujibond) that are more resilient to the chemical properties of synthetic oils compared to older materials. 
These technical guides detail the process of removing a Subaru engine and common points of oil seal and gasket failure:
18:55
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    Mar 26, 2023 — So I work at Subaru and about 3k is what's required to fix that specific leak. Cam carriers tend to leak on the non tu...
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