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Conventional or synthetic oil?

2011 Subaru Outback 3.6L
The dealer has 2 charts that indicates I should use conventionalc oil.
The manual says I should use synthetic oil.
The chief mechanic says the car “calls for” conventional oil and that the manual was printed in 2010 and was wrong.
The manual Owner Manual refers me to the Warranty and Maintenance manual, which I do not have. He cannot find a copy of this manual on line either.
The oil level gauge says 5W30 but does not indicate conventional or synthetic.
The car has 80,000 miles on it and it loses about 1/2 quart of oil per 5000 miles. Not anything I am concerned about.
The car is running fine and I hope to keep it for several more years. So moving forward, should I use conventional or synthetic oil?

The manual say use synthetic, so use synthetic. The chief mechanic, in my opinion is wrong. 1 quart per 10,000 miles if wonderful oil consumption. I’d think you want to do everything you can to keep it that low.

Just a side note, I use synthetic oil in EVERYthing I own with an engine whether it calls for it or not. It is cheap insurance. A new engine costs thousands versus 200,000 miles of synthetic oil changes which cost hundreds.

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Oil threads have no half life which is why one auto forum has banned them . That said I just did a Google thingy and found a chart by a Subaru dealer and it show 2011 Outback as using 5W30 Conventional .

Frankly , my feeling is just put oil of your chice in and keep an schedule to check the level and changes.

Read this discussion. Based on this, I’d go with full synthetic oil (not synthetic blend) even though you don’t have a turbocharged engine. This is not an inexpensive change if you pay someone to change your oil. A quick lube place I’ve used for years charges $40 for regular mineral oil, $60 for synthetic blend, and $90 for full synthetic. It might cost them $5 more for the synthetic blend and $10 more for the full synthetic oil, but probably it’s half that in bulk. In any case, the difference in cost from mineral oil is basically all profit. If you are faced with a similar situation, get the synthetic blend for this oil change and then find another place with more realistic oil change prices to do it in the future.

It’s not turbo, GDI, or European made, so IMHO conventional would be OK.
Anyway, most of today’s “dino” oils are part synthetic.

And most of today’s synthetic oils are suspiciously dino based… :roll_eyes:

Per a Google search;

In the late 1990s, Castrol started selling an oil made from Group III base oil and called it SynTec Full Synthetic. Mobil sued Castrol , asserting that this oil was not synthetic, but simply a highly refined petroleum oil, and therefore it was false advertising to call it synthetic. In 1999, Mobil lost their lawsuit .

I found the owner’s manual through the Subaru website in about 1 minute.
The maintenance section is in the Owner’s Manual (11).
It’s quite specific about what oil to use-

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The referenced maintenance schedule is a royal CF on the part of Subaru. Still nowhere to be found on their site. Found other links to the info. Here’s one-

All my vehicles calls for conventional 5W30, and I switched them all to synthetic 5W30. At this viscosity rating, you can switch back and forth really, but If your manual says to use synthetic, just use synthetic. :grinning:

I really like the 0w30 stuff but it’s not as easily found on sale.

Thank you, Twin Turbo. I have this manual and have read this.
The issue is, there are 2 Surbaru charts that the Subaru maintenance department have shown me that indicate to use conventional oil and the intake person recommends this when I take the car in.
Also, the pages that you have kindly posted for me indicate that there is a Warranty and Maintenance manual, which I do not have and neither does the Subaru maintenance person.
The maintenance dept person believes the chart and says the manual is likely wrong. I know, it seems unlikely but he said manuals are sometimes printed early…
I will try to post the chart.

Bottom line:
if synthetic is required, you must use that
if it is NOT required, you can use regular or synthetic.

In other words, you can always use synthetic.

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Thank you, everyone. I will stick with synthetic.

What is a royal CF?

Nothing for public consumption…

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Cluster #!!&


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Hahaha. Thanks.

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My second post has a link to the schedule but bear in mind, that is only to define how often to change the oil. The Owner’s Manual dictates which oil to use.

It is now 7+ years since that manual was printed. If there were errors, they would have been corrected by now in the online resource- which matches your printed manual from 2011 does it not? You can also look at years before and after and they basically call out the same thing. Who do you trust- the people that made the car or those that are servicing it? Usually, conventional oil is cheaper than synthetic. If they charge X dollars to do an oil change but use conventional oil, they make more profit on the materials…or entice people in with a lower price if it is appropriately priced based on oil type. They are in business to make money in an ongoing fashion from your purchase. The car manufacturer already has your money for the car, they have no incentive to push conventional oil at this point. Follow the manual. If the dealership doesn’t want to do that- find someone else to change your oil…