Is Early First Replacement Best? Convinced After Seeing the Extracted Gear Oil (Subaru Impreza G4 DBA-GJ2)

This is a statutory inspection of an Impreza G4 with extremely low mileage, over 8 years old.

2013 model DBA-GJ2 FB16 CVT with 9,000km mileage

The owner requested an inspection focusing on lubricants, as the vehicle will be driven more frequently in the future.

First, I opened the hood to visually inspect the fluids.

The first thing that caught my attention was the excessive amount of coolant in the sub-tank. It was far above the MAX level.

Long Life Coolant transitioned to a high rust-protection type about 20 years ago when Toyota made the change, after which other manufacturers gradually replaced their coolants with similar high rust-protection types.

Toyota and Daihatsu use “pink” coloring, while other manufacturers use “blue.”

I believe this blue color is the source of confusion. The excessive foaming of the dripped coolant suggested a high possibility of washer fluid contamination, so I carefully performed a complete fluid exchange.

Foaming can cause cavitation, leading to serious problems like water pump impeller erosion. To avoid such human errors, I believe a color other than blue would be preferable.

Since the engine oil had already been changed, I proceeded with the brake fluid exchange and then raised the vehicle on the lift.

This Impreza has a longitudinally-mounted engine with front-wheel drive.

The transmission combines the front differential and transmission (CVT) in one unit, but the differential section and CVT section are separated by a partition and lubricated with different oils.

The genuine CVT fluid comes in a minimum container size of 20 liters. Considering the current mileage and initial cost, I decided against replacing it this time.

However, the owner wanted to replace the front differential oil, so I decided to proceed with the replacement, though it seemed a bit early (manufacturer recommends every 40,000 km).

The differential oil drain bolt is a Torx T70, among the largest sizes.

You can see the size difference compared to the most frequently used T30.

When loosening, you typically encounter adhesion, requiring much more force than the specified torque. The tools used for this must be reliable.

Though the mileage was under 10,000 km, the magnet inside the drain bolt had collected lots of iron powder and needle-like metal fragments.

Similarly with FR (front-engine, rear-wheel drive) cars or four-wheel drive rear differentials, transmission devices where rotation axes intersect may have contaminated gear oil at the first replacement.

I filled it with the specified Subaru Extra S 75W90 GL-5 differential oil.

Subaru Gear Oil Extra S (75W-90) 20L Pail Can Cosmo Oil Lubricants K0322AA093

The bolt circled in red is called the “overflow drain plug,” which requires a special oil level adjustment.

Behind this overflow drain plug is a “tube” of a certain length.

First, I loosened the overflow drain plug.

A small amount of contaminated gear oil came out.

Then, when I pour gear oil into the filler located on the driver’s side of the transaxle,

It overflows like this, allowing the correct amount to be filled.

Finally,

Since the vehicle will be used in areas where de-icing agents are spread, I completed the inspection and maintenance by high-pressure washing the undercarriage, thoroughly drying it, and applying clear rust-preventive coating across the entire area.