I read everywhere Subaru owners go for the T6 5w40? Or is that strictly a turbo thing?
That was mainly for the older EJ series engines.
These are the FB20 and FB25 engines.
I know with other Japanese Manufacturers I4's its the oil control return holes plugging that are the primary cause of oil consumption. A combination of oil with a "weak" flash point and a small, hot running aluminum block can overheat the oil, flashing to hardened carbon in the arteries of the piston. With nowhere to scrape oil off to, oil builds up in the cylinder the faster you go. Jamming up the rings with burned up oil. In that case going thicker only helps after the clogging has occurred. restricting flow with thicker oil. The fix is not rings. Its a piston removal to clear the holes with a drill, or replace pistons entirely.
It has to do with the low tension rings(for fuel economy) and burning oil. These engines are horizontally opposed 4 cylinders so you cant just slap in generic "knowledge" about Asian I4 engines and call it a day.
Its been widely documented that they have been through at least 3 different ring part numbers.. but often replacing the rings doesnt fix the issue so you get a new short block.
I had 3 different fb25 powered subarus.. all in the problem list.
Its an issue caused by the search for better MPG. It in no way shortens engine life.
The issue was also further caused by lengthened oil change intervals.
The oil burning accelerates as the oil ages in service.
I'm curious about this test. It's likely a dealer oil change with a seal on the oil filler cap and dip stick tube, since it has an electronic oil level sensor. Does anyone know what the Subaru dealer test procedure is?
The procedure varies somewhat.. foresters from 2011-2013 did not have any kind of low oil level light. 2014+ have the Low engine oil level light.
Outbacks from 2013+ did (all fb25 outbacks)
unsure about crosstrek/impreza
Yes they change the oil and seal the system then instruct you to drive for about 1000miles or until the light comes on (depending on model and year)
they then measure the level. 1/3quart usage in 1000 miles is failing.
Many dealers will overfill the oil when changing it. for example on the 2013 outback oil burner they put almost 12 extra ounces in.
That car has seen new rings, a new shortblock, and the new shortblock is now consuming oil after 15000 miles...
Consumption in an oil change accelerates as you get more miles on the oil.
1qt in first 3000miles 2nd quart around 5000miles(2000miles) additional .5qt before the oil change.
Consumption is best in around town driving. Worst on extended high speed trips.. example: 80mph on Interstate route 80 in PA(hilly)