Please refer to the thread about my 2017 Outback 3.6R.
After going through the BS with a certain Subaru Service Tech, I am using Synthetic 5W-30 and in the manual it says if the customer prefers to use synthetic oil, use 5W-30 and change at Subaru recommended intervals (6,000 miles or 6 months.)
The things the service tech said (for example; Subaru does not recommend using synthetic in the 3.6 R because the 3.6 runs hotter") were utter nonsense and I told him that what he was saying in so sense at all and what he was saying was opposite to everything I read about the benefits of using synthetic oil.
To confirm, I wrote Subaru and the response was as follows:
“Thank you for taking the time to contact Subaru of America, Inc.
Regardless if you use conventional or synthetic engine oil for your 2017 Outback 3.6R Limited, we recommend oil changes every 6,000 miles or 6 months, whichever comes first. Our maintenance schedule is found in the 2017 “Warranty and Maintenance” booklet. A copy of this booklet should be in your glove compartment. If not, please let me know and I will send you one.”
Thank you for the opportunity to be of service.
Sincerely,
John J. Mergen
Subaru of America, Inc.
Customer/Retailer Services Department
1-800-SUBARU3 (1-800-782-2783)
Service Request Number: 1-30946205872
In summary, there are levels of synthetic (depending on refining process) or you can buy full synthetic. I have opted to use Subaru 5-30W synthetic.
In the past and on my other cars, I would never run conventional motor oil more than 3,000 miles and, for example, when I pulled the intake manifold and valve covers on my 1995 Grand Cherokee 5.2 L V8, the inside of the engine was free of sludge and compression was excellent for and engine with 190,000 miles on it. I bought it when it had 13,000 miles on it and maintained it myself.