What oil should I use - Subaru Legacy 2018

Joined
Jun 10, 2018
Messages
2
Location
Eastern N.A.
Hi gang,

Looking for your input regarding the following vehicle. It was purchased new about a month ago, so I'm starting to think about my oil change game plan.

The basics:
  • 2018 Subaru Legacy 3.6R - 6 cyl
  • Owner's manual recommends 5w30 conventional oil, at 6,000 mile/6 month intervals.
  • API classification SN "resource conserving" or ILSAC GF-5 certified.
  • I live in a very cold part of the continent. The winters get very frigid at times, we're pretty much guaranteed to hit -20 degree weather at least a few times in the season.
  • The car does an 15 mile (one way) commute every work day. 10 miles of that is easy highway cruising. But I make sure to exercise my 6 cyl boxer with some hard accelerating once in a while... it would be unfair to the car otherwise
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  • Car is brand new, and I made sure to baby the engine on its first 1000 mile break-in. Engine is purring along very nicely so far.



So based on my early limited knowledge of PCMO's, this is what I am considering. I am looking for any input to confirm if my line of thinking is correct, or if people would do things differently.
  • Based on my shorter than average commute, it's looking like I'll have to change the oil twice a year if I'm going to stick with conventional. But perhaps, after the warranty runs out I am wondering if there are any ill effects to changing it only when that 6,000 mile counter expires? What is the detriment to leaving the oil in the car for, say, 9 months instead of the recommended 6? Perhaps this duration will be longer if I opt for extended OCIs with a synthetic oil.
  • I'm scratching my head over the "...however 5w30 synthetic may be used for optimum engine performance" blurb on the owner's manual. (image above.) I am wondering exactly what "optimum engine performance" entails?
  • I hear that a synthetic 5w30 has better cold engine performance compared to a conventional 5w30, because the oil covers all of the moving parts in the engine quicker, immediately following starting of the engine. Is this true? If yes, how much of a difference does it make? As an example, if conventional 5w30 is going to allow the engine to last for the normal 200,000 miles or so even with the -20 winters then I'm not too concerned about spending more for synthetic just for the extra protection.
  • If I do decide to go for a synthetic oil, what OCI do you guys think I can safely work with? (after the vehicle warranty expires, of course)
  • Finally- is there any detriment in doing my first oil change before the 6 month/6000 mile mark? I heard that some new cars come with a special oil used for engine break-in (?)

Thanks in advance to the community for helping me keep my baby in tip top shape
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I would put any 0w30 oil you can get on sale. They all seem to be pretty decent. The 0 WILL BE GREAT FOR COLD WEATHER.Make sure the oil you buy has those labels.

After warranty, I would go 0W20 EXTENDED performance oils. You would have to do some UOA to figure out how long it would last. My last OIL CHANGE WAS 13,000 KM and lasted a year and a half. The analysis revealed the oil was still good and to retest in a couple thousand miles. I just changed it for the heck of it.

I would guess optimum performance would be max HP/torque, reliability, etc. Basically saying, we designed it to run on this oil and if you run something else we can't guarantee it will work as well.

Based on your mileage you could probably do them once a year.

My apologies for the caps, keyboard was possessed.

Congrats on the new purchase and enjoy the beautiful vehicle!
 
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Any 5w30 that meets the spec will be fine. I would not run 0w20 in that engine.

Castrol or Valvoline would be my personal choices, or maybe the new Rotella T6 5w30 multi vehicle.
 
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Synthetic 5w-30 that meets spec.
I would check the Sube forum boards about a special factory fill. Can't say that's a reliable source but what are your research options?
If it was my car I would change the factory fill at 5,000 miles. I have no data backed reason for this. Just what I would do.
 
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If that is the Subaru engine with the long and convoluted timing chain then I would recommend a major brand of synthetic that meets the owners manual recommendations. 5w30 or 0w30 would run well in that engine. The brand choice would be up to you.
 
I will stick with a great oil choice for my recommendation, PP 5W30. Completely ignore the comment to run 0W20, you'd be a fool to run a 20 weight oil in any EJ/EZ engine. 3.6s are pretty easy on oil, and yes, you could make it to 200k easily on today's conventional 5W30s @ 6k intervals. It's your call, but for my money and SOPUS rebates, I'd stock up on the PP while it's on sale and use that.

Nice car, enjoy it!
 
1. Yes I would do synthetic since you are in a colder climate.

2. I'd stick with 5W-30 during warranty, but the 0W-30 advice above is not bad.

3. Pick any major brand, or your favorite color of bottle of any major and you can certainly sleep well.

Long time Subaru owner here. Always owned the 4 not the 6, but they are great cars. I'm assuming winter driving is on your agenda. You made an EXCELLENT choice.
 
Former 2015 Outback owner here. To keep the Subaru warranty people from getting twisted in the unlikely event you had an engine problem, I'd leave the factory fill in for 5K miles. Then I'd change to any 5w-30 full synthetic that meets your API rating. I would do 6K mile intervals with a new filter regardless of time. Use Subaru filters if you choose, but there's lots of quality filter choices for a 6K mile interval.

Welcome to the forum.
 
5W-30 synthetic year around.

0W-30 synthetic in the winter.

I do this with excellent results for the past 5 years in my 2013 Subaru Outback with the same 3.6L as yours.
 
Just today, I was reading some reviews on Rotella T6 and there were numerous positive reviews from Subaru owners. I have no experience with Subaru's. I just tried Redline in my signature for the first time and so far I am impressed. I will be trying T6 in future.

I would google UOA's with your engine to make an informed opinion, coupled with the aforementioned recommendations. A lot of great wisdom on this forum. You will learn more than you ever knew existed. Some PHD's here too!

Good luck and welcome to BITOG mania! Let us know the outcome....


Respectfully,


Pajero!
 
Originally Posted By: Pajero
Just today, I was reading some reviews on Rotella T6 and there were numerous positive reviews from Subaru owners. I have no experience with Subaru's. I just tried Redline in my signature for the first time and so far I am impressed. I will be trying T6 in future.

Respectfully,


Pajero!


I have a bunch of it I bought for $1/quart. It may find it's way to my Subaru at some point - out of warranty of course
 
QSUD 5w-30 maybe in winter and 10w30 in the warmer months. Get a block heater for the cold months - don't rely SOLELY on oil grade.

If you want to step up for the winter to a real synthetic - try ENEOS Sustina. The latest Subaru ( Idemitsu) 5w30 for the WRX STI should be good esp if you like moly. Im not so sure regarding ring sticking with boatloads of moly. Oils formulated this way seem to FAIL both TEOST certification tests. Ow20 in the recent past have been given an exemption on passing TEOST with a formulated high moly dose.
 
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