Hi, John.
No, I would not recommend going with a thicker oil than recommended by the manufacturer, and you are right to continue using the 0-20.
It is tempting to add things like stabilizers and sealing agents, but the truth is they will not stop the issue, and many will gum up the engine.
That said, it is normal for a quart to go in 7500 miles, and though it is concerning watching it go from no loss to 1 quart, it actually is not hurting anything.
If you feel it becomes excessive, a compression test will let you know if you have leaky piston rings, and a small puff of blue smoke when starting the engine cold will let you know the valve stem seals are leaking.
Hi John, I have experienced the exact same issue beginning in the summer of 2015. I also believe I was in the same mileage range you are beginning to see this occur.After MONTHS of dealing with the dealership's maintenance department where I purchased my Forester It pretty much came down to "yea that's going to happen." If you feel like it, take it to your local Subaru and ask to undergo an oil consumption test. They will replace and fill your oil and will get you to bring the car back in every 1500 miles to check the oil level. If your loss is greater than 1 quart per some mileage they can request some repairs. Unfortunately mine was outside of that range and now i just keep and extra quart under the seat for emergencies. It may also help to see if where you get your oil changed has free top offs- My local Jiffy Lube will top off if driven less than 3500 miles since last oil change. Hope this helps and you avoid the headache I had to go through for this answer!!
