[Bibo]

I have a 4 cylinder 2015 Outback and I love it....but I have always thought using 0-20 weight oil is very thin oil (yeah I'm a woman and that's how I look at it lol). I was talking with another Subbie owner and he said he uses 5-30....

So would it hurt to use a thicker oil? I mean I am in Illinois and its hot here so why not?

Your thoughts.....pros and cons please and if so, why?

 

[mikelipke]

Why not?
Because the engine was designed for 0-20. Literally.
Don't try to out think the engineers.

 

[Bibo]

So when its 90 outside and I hear a tick tick tick in the engine but not when its in the 60's that's not the oil not protecting the engine?

 

[Quartermaster_James]

So when its 90 outside and I hear a tick tick tick in the engine but not when its in the 60's that's not the oil not protecting the engine?

I'm no engineer, but I suspect that a thirty degree variance in atmospheric temperature has little effect on the operating temperature of the engine and the oil's ability to protect it.
Ticking might occur with a low oil level. Or it could be something else entirely. I usually think of exhaust leaks as making a ticking sound, though some people describe valve train noise as "ticking" too.

 

[FirstSubie4me]

The engineers and designers know what they are doing. Oil shares the HEAT REMOVAL and LUBRICATION jobs. Thin oils reduce friction and carry heat away faster. They can suspend smaller, more effective additives that are 'lost' in thick oil. Thin is good. Old engines need thicker oil because tolerances are greater and they were designed for it. bobistheoilguydotcom

 

[frankb]

Why not?
Because the engine was designed for 0-20. Literally.
Don't try to out think the engineers.

I seem to remember reading that in some countries they specify 5-30 in the same engine? 0-20 is for a slight increase in mpg.

 

[KentuckyOutback]

^
^
^
What the cat said, LOL! Putting 5-30 won't hurt the engine, it'll just take your MPGs down a little.
I was raised around mechanics, and they explained to me that different weights of oil are for different environments.
Back in the before time, Auto manufacturers used to specify different weight oils, for different climates.
In the summer they might specify 10-40, and 5-30 for the winter.
While I seriously doubt 5-30 will hurt anything, I wouldn't go any thicker. And for winter, go back to 0-20.

 

[z28dug]

Oil viscosity never used to be a big deal. That has changed with modern engines having variable valve timing. Most use oil pressure to operate the variable valve timing. They are engineered to ideally function with a specific viscosity oil. Wrong oil can muck with the works.

Unless you are a mechanical engineer, why would you want to second guess the Subaru engineers?

 

[mikelipke]

I'm still waiting for evidence of any engine failure or early demise of any modern engine, made by any manufacturer, caused by the use of 0-20 oil.

 

[Rub]

Engineers don't have editing authority and the content in the OM is not solely their own words free from marketing or lawyer input.

The one thing the manual does not and cannot predict is how you will use your car and in what conditions. The blanket oil viscosity recommendation is based on a range of assumed uses but is by no means definitive. This is why the manual of virtually of all manufacturers have clause suggesting a higher viscosity if you track, tow and so on. There are no statements in the OM that say the engine is compromised or will kaboom if you don't use 20 wt oil.

Yes, you can safely use a 30 wt oil and sleep well at night. You will take a slight mpg hit but these lighter 20 and now 16 wt oils are CAFE driven.

Buy the Mobil1 0w-30 AFE at Walmart and rest easy.

 

[1 Lucky Texan]

I'd like to know if the same engine sold in the European markets has the same oil vis. recommendation.

 

[pduncan]

The engineers that design these engines put them through hours upon hours of testing in all kinds of conditions. The fact that we are in the 4th year of this engine- oil combination and they have not changed their recommendation or what oil they ship in the engine should tell us all something. If they were seeing premature failures, they would have changed it by now. That would be money out of their pocket.

Trust that the engineers know what they are doing. Most complaint about 0-20 is you can only get synthetic and it cost more.

 

[Bibo]

Thanks for all the input....
I found the following article and it makes sense. Since I have a 4 cylinder, I will stay with the 0-20 weight...I guess my concern was thinking back at the OLD 4 cylinders where you could hardly accelerated enough to get on the freeway lol (yep I am 62 years old...and remember the 'whining' of 4 cylinder engines as you tried to accelerate fast!)

I didn't realize that they now recommend synthetic oil in 2015 and newer cars. My dealer uses Valvoline, I have them use Mobil 1 in my car....and interesting they NEVER mentioned that synthetic is now recommended nor that Subaru has now brought the change interval timing down to 6,000 miles from 7,500.....I always do it at 5,000 and rotate my tires at the same time. (Most of my driving in city driving, so there's alot of turning and corners versus straight aways)

Thanks again!!


Subaru Synthetic Oil - Which Cars, How Often, Exceptions, FAQ

 

[Bibo]

Can't get link to add....so this is it in pieces

www. manchestersubaru. com/subaru-synthetic-oil.htm

 

[idosubaru]

Fact - you can use thicker oil without issue.

Fact - navigating information on this topic is too complicated for most people - so you should just follow the Subaru owners manual.

Problem - There's zero consensus and it's mostly opinion. Unlike 'engine rebuild' and 'transmission rebuild' and highly technical questions which generate replies with compelling insight....not so with oil - anyone and everyone comments.

What you want is to hear from the best of the best - but they're simply not easily available. (high capacity people rarely spend gobs of time discussing easy mundane things like this - they're actually building, creating, and leading the way forward). So you won't hear from guys that are incredibly valuable in their experience, backgrounds, and capacity to talk quantitatively about this stuff rather than just regurgitate whatever fits their suspicion/desire. Here's two of them that repair/build engines better than Subaru and beat the average by an order of magnitude, and can talk about practical platform specific Subaru information better than almost every one. I've spoken with these guys and they are incredibly sharp and got there by extensive high capacity learning and attention to detail from any angle - not taking stands:

Ivan'simports in Canada
Owner of this place: https://www.facebook.com/superiorsoobie/

There's more, but the top notch folks are rare. What you'll get from this forum is woefully short of what they could teach on this subject. These guys have learned their views, not just staked them out on preconceived notions or the unicorns of "subaru engineers" et.al.

Ideally you learn from guys like that - but that's highly unlikely - so stick with the owners manual.

"Subaru engineers" - The magical wizards that have added additional failure modes that never previously existed in Subaru's: EJ25D piston protruding headgasket blowing, Phase II headgasket weeping, rear separator bleeding, wheel bearing eating, caliper pin bushing seizing, low grade head repair non-resurfacing, FB oil control ring consuming, EZ engine internal HG failing....and more...

I totally get it - there's so much information who do you trust? best to trust Subaru, that's a great starting point and due to the issues outlined above - probably needs to be the end point for most people.

So follow Subaru. But there is a more compelling and robust take on "oil topics" than what you typically hear and read about online. By and large oil choices are way over played and magnified. Everyone thinks they're awesome because they got 200,000 miles on XYZ....when in reality that's just normal and eveyrone else that doesn't even care about cars drives 200,000 miles on whatever oil is on sale.

I just prefer a complete and accurate picture of what's going on - even if it means the OP lands in the same boat - follow the owners manual.

I'm still waiting for evidence of any engine failure or early demise of any modern engine, made by any manufacturer, caused by the use of 0-20 oil.

I think lack of oil is the main issue, not weight. Could that same statement be applied to those running heavier weight oils? No issues there either.

But either way - control rings are the issue so oil choice is probably a cheap band aid at best?

 

[z28dug]

Fact - you can use thicker oil without issue.

Fact - not hard to find techs that have found trouble code P0521 being set by the wrong viscosity oil being used.

Why do owners feel the need to ignore what the manufacturer calls for?

 

[Rub]

Fact - not hard to find techs that have found trouble code P0521 being set by the wrong viscosity oil being used.

Why do owners feel the need to ignore what the manufacturer calls for?

Why is it that with the engine oil recommendation - not the mandate from the OM - must be followed blindly but for everything else, people deviate or stray from OEM all the time. You don't put on the OEM tires, bulbs, floor mats, head gaskets, belts, bearings, light bulbs, LED upgrades, towing hitch. The list goes on.

If you're curious, over at BITOG there is a thread where Ford engineers and teardown guys are quoted as saying that 20wt is done for CAFE purposes and that better protection comes from 30wt.

On your P code, can you point to online sources where teardown people demonstrated that it was thrown because a 30 wt oil was used instead of 20? Not a 15w-50 or something else but where a 5w-30 was used instead of 0w-20 or 5w-20?

If you want to get real deep into the cSt numbers, there are 20wt oils that are so close to being a 30wt in viscosity and there are 30 wt oils that if there is a skosh of dilution, they drop into 20wt viscosity.

 

[idosubaru]

Fact - not hard to find techs that have found trouble code P0521 being set by the wrong viscosity oil being used.

Why do owners feel the need to ignore what the manufacturer calls for?

thank you that's the problem, people quote and rely on anecdotal reports as a universal truths. They don't all set that code and there's gobs of people running 5w30, I've never heard of that happening. Please post a source and reference.

Also as he just said its routine not to folllow the manufacturer. They're the best starting point. They are absolutely the best starting point and only deviate with compelling high capacity well versed information. They're recommended head gasket repair and piston slap repairs aren't the best options, that is absolute fact. And on and on and on we can go.

And I reiterate - we are in agreement on what to recommended to the OP and most people - follow subaru. I made it abundantly clear.

most folks won't be willing to change their mind and learn. They won't ask how and what those people I mentioned do and look up information from them and compare and contrast real world data from the best of the best. That's how I do things. Some people like that, some don't care. So it's pointless to debate.

 

[Rub]

I think the SN recommendation in the manual fits most poeple but it's not a bible or chisled on stone tablets.

It's a starting point for everyone or it can be the only point for those who don't dig deeper. That's fine too.

Edit - The P code is for a variety of oil issues and viscosity is not one of them. High pressure, low pressure, no pressure, bad sending unit but not for 30wt in a 20 wt.

 

[z28dug]

There are any number of websites offering checklist on resolving a P0521 that list wrong viscosity oil as a possible cause.

Look at Chrysler P codes and P1521 is specific to wrong viscosity oil.

People should not preach it OK for an owner to do something when they will bear no responsibility for the consequences.