Our Subaru does not seem like the quietest thing in the world, although it is pretty serene inside the car under most conditions.
2.5 liters is on the large size for a four, HO or not. The larger Hondas, like our current 2.2 and 2.4 are nothing like as smooth as our old 1500 Civics, for example, even with balance shafts.
I have selected GC for this reason. It is fairly thick and so should damp down any noise.
I changed the factory fill at 990 miles, ran QS 10W-40 for the next 3K, mainly because I had it and Subaru allows it, and then ran 5K on QTorque 5W-30, because I had it.
I then put the car on a GC diet at 9K.
It will get its second fill of GC at 14K, probably in December.
I have been using M1 filters.
Now, is it just my impression, or does the flat four, even NA, reach unusually high bulk oil temperatures?
I ask because on the three drains I have done, the oil has always come out like water. This could be because, while the drain plug has a 17mm head, like any Honda, it is unusually large in diameter, which may allow the oil to drain more quickly, which would give me the impression that the oil is unusally thin.
I always drain all engines hot. That way, you get the opportunity to scald your hands, and to singe your fingertips on the filter
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