Decided to change the factory-fill rear differential fluid on my ’21 Forester at 30K miles today. Glad I did it, but what a PIA it was. It was a tougher job than I expected, and the old fluid looked incredibly dirty. And yes, the drain plug magnet had a big glob of junk on it.
Even with the car on jacks, I had to use a socket extension to get access to the upper fill plug. Otherwise, the plug was too close to the bottom of the frame for my socket to reach the plug. The biggest surprise was how incredibly difficult it was to remove the factory installed washers from the drain & fill plugs once I had them off. They were simply stuck to the plug, and I had to push a knife blade between the washer and plug to get them separated. It was not easy. The dealer gave me an “interchangeable” washer that looked like an oil drain plug washer instead of the flat differential washers that the factory used. Still, the news ones seemed okay once used.
I was not pleased with the old fluid that drained out. It was not clean looking at all. So dark in fact that I decided to send a sample off to Blackstone Labs for an analysis. Plus, not much came out. Roughly 24 ounces as best I could tell. The owner’s manual states that the rear diff takes about .85 of a quart (about 27 ounces) when refilling, but I ended up putting in almost a full quart before the new fluid started draining back out of the fill hole. And yes, the car was level when I did the work. Pics below basically tell the story.
Depending on what Blackstone tells me, I may take the car back to the dealer and pay the $$'s for them to change the front differential fluid. Too much work for this old fart, and I have no faith in any "lifetime fluid" song & dance I hear from dealers anymore. Anyway, that's my experience today.
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Even with the car on jacks, I had to use a socket extension to get access to the upper fill plug. Otherwise, the plug was too close to the bottom of the frame for my socket to reach the plug. The biggest surprise was how incredibly difficult it was to remove the factory installed washers from the drain & fill plugs once I had them off. They were simply stuck to the plug, and I had to push a knife blade between the washer and plug to get them separated. It was not easy. The dealer gave me an “interchangeable” washer that looked like an oil drain plug washer instead of the flat differential washers that the factory used. Still, the news ones seemed okay once used.
I was not pleased with the old fluid that drained out. It was not clean looking at all. So dark in fact that I decided to send a sample off to Blackstone Labs for an analysis. Plus, not much came out. Roughly 24 ounces as best I could tell. The owner’s manual states that the rear diff takes about .85 of a quart (about 27 ounces) when refilling, but I ended up putting in almost a full quart before the new fluid started draining back out of the fill hole. And yes, the car was level when I did the work. Pics below basically tell the story.
Depending on what Blackstone tells me, I may take the car back to the dealer and pay the $$'s for them to change the front differential fluid. Too much work for this old fart, and I have no faith in any "lifetime fluid" song & dance I hear from dealers anymore. Anyway, that's my experience today.
