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Discussion Starter · #1 ·
Are there any concerns over what oil to use if these recommendations are followed? I use Mobile 1 in my 2017 Forester. All 0-20w.
User Manual Information:
Always use the SUBARU approved engine oil. For further details, please contact your SUBARU dealer.
If the approved engine oil is unavailable, use the alternative engine oil described on the next page.


API (American Petroleum Institute)
classification SN with the
words “RESOURCE CONSERVING” OR
ILSAC (International Lubricant
Specification Advisory Committee)
GF-5, which can be identified
with the ILSAC certification
mark (Starburst mark)
 

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While I'm sure someone will shout me down I think as long as you are using synthetic and the proper 0-20W you should be fine.

I will probably be using Amsoil as it is only a little bit more expensive than Mobile 1. I think with how easy it will be to change compared to my current vehicle I will probably do oil changes every 3,000 miles as well which is probably just as important if not more so than what brand oil you use. The other part of the equation is the filter and that I'm not sure what to use yet.
 

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The 0w Mobile 1 oils have been problematic for several brands in the Non Euro spec bottles. Which is what is typically sold here in the US regarding Mobile 1. Sometime around 2006ish Mobile 1 started selling a cheaper non Euro spec oil here in the US. I ran all my cars on it and all of them had to be switched to another brand after 2006. All of them saw a big spike in oil use. This was a big topic in other Subaru forums given many of us had similar experience. The discussion led to the discovery that the 0weight oils some clearly more than others have a much higher volatility rating meaning they have a higher evaporation rate.

I switched to Chevron oils and haven’t looked back. My Mercedes which has no less than 9 stickers under the hood requiring Mobile 1 gets Rottella oil. The problem being the Euro spec Mobile 1 is expensive and difficult to get here in the US.
 

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There are a couple oil forums that go in-depth towards the use of 0w20's and in particular the NOACK value. This is what you'll want to look for. I think the rule of thumb was to try to find one as close to or below 7% as possible (it will be extremely hard for a 0 weight to have a NOACK of 7% or less.)

Personally I'm going to just run the true OEM Subaru oil for a bit - manufactured for Subaru by Idemitsu. The used oil analysis are pretty impressive on them, but only you can make that judgement for yourself.

New model, new engine, the last thing I want is any complications in trying to get any warranty related repairs covered.

A certain big chain sells a 5qt jug of M1 for around $22, usually with a ~$10 rebate floating around from the manufacturer, so it's easy to stock up. But, easier doesn't necessarily mean better. The dealer quoted a synthetic oil change at $70 for a 4-banger, and about $95 for the 6-banger (for the OB/Leg)

Overall the issue with the evaporative issues are oil droplets that are getting deposited on the intake valves after EGR - which creates carbon issues along with unburned gasoline droplets that also get recycled. This is why many manufacturers - not just Subaru - suggest TOP TIER gasoline (more detergents), and using a specific grade and certification of oil. You can't just dump in a can of Techron to clean out the intakes with Direct Injection. It is a multifaceted issue.
 

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There are a couple oil forums that go in-depth towards the use of 0w20's and in particular the NOACK value. This is what you'll want to look for. I think the rule of thumb was to try to find one as close to or below 7% as possible (it will be extremely hard for a 0 weight to have a NOACK of 7% or less.)

What are those forums?
 

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I don't now the rules about cross posting to other forums. I'll privately message you.
 

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There are a couple oil forums that go in-depth towards the use of 0w20's and in particular the NOACK value. This is what you'll want to look for. I think the rule of thumb was to try to find one as close to or below 7% as possible (it will be extremely hard for a 0 weight to have a NOACK of 7% or less.)

Personally I'm going to just run the true OEM Subaru oil for a bit - manufactured for Subaru by Idemitsu. The used oil analysis are pretty impressive on them, but only you can make that judgement for yourself.

New model, new engine, the last thing I want is any complications in trying to get any warranty related repairs covered.

A certain big chain sells a 5qt jug of M1 for around $22, usually with a ~$10 rebate floating around from the manufacturer, so it's easy to stock up. But, easier doesn't necessarily mean better. The dealer quoted a synthetic oil change at $70 for a 4-banger, and about $95 for the 6-banger (for the OB/Leg)

Overall the issue with the evaporative issues are oil droplets that are getting deposited on the intake valves after EGR - which creates carbon issues along with unburned gasoline droplets that also get recycled. This is why many manufacturers - not just Subaru - suggest TOP TIER gasoline (more detergents), and using a specific grade and certification of oil. You can't just dump in a can of Techron to clean out the intakes with Direct Injection. It is a multifaceted issue.
Have you also looked into the use of low SAPS(low sulfur) oil in Direct Injection(DI) engines ? You seem to have done some research into this subject (OIL) and would be interested in what you have found out, what you think about this theory(?) , that low SAPS “helps” prevent deposits....
Fact or fiction?
 

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While I'm sure someone will shout me down I think as long as you are using synthetic and the proper 0-20W you should be fine.

I will probably be using Amsoil as it is only a little bit more expensive than Mobile 1. I think with how easy it will be to change compared to my current vehicle I will probably do oil changes every 3,000 miles as well which is probably just as important if not more so than what brand oil you use. The other part of the equation is the filter and that I'm not sure what to use yet.
...I plan on going w/Motul or Eneos, but I'm not sure if I'll stick with 0W-20 though.
 

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While I'm sure someone will shout me down I think as long as you are using synthetic and the proper 0-20W you should be fine.

I will probably be using Amsoil as it is only a little bit more expensive than Mobile 1. I think with how easy it will be to change compared to my current vehicle I will probably do oil changes every 3,000 miles as well which is probably just as important if not more so than what brand oil you use. The other part of the equation is the filter and that I'm not sure what to use yet.
I know that many of the Amsoil adherents have an almost cult-like attraction to their products but it is true, it is a very good synthetic oil.

Some of the oils I would recommend looking at;

Amsoil 0W-20 Signature Series
Mobil 1 FS European Car Formula
Quaker State Ultimate Durability
Valvoline Full Synthetic High Mileage with MaxLife Technology
Valvoline Modern Engine Oil, for engines 2012 and newer
 

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Discussion Starter · #10 ·
Thanks for all the replies. I think I will most likely go with Amzoil 0w-20. Since I believe it is important to stick with manufacturer recommendations I won't use a heavier viscosity oil, especially with a new turbo. I buy Subaru filters by the case so I will continue with them. I also will install a Fumoto drain plug. As far a how many miles between changes, I'll try and make the first change at 3,000 and every 5.000 after that if the oil remains clear. Thanks, that's my plan and I always like a man with a plan.
 

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Yes, definitely stick with the recommended viscosity. With tight engine tolerances these days I’d be concerned that a heavier oil wouldn’t be able to flow to areas that it needs to lubricate.
 

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Thanks for all the replies. I think I will most likely go with Amzoil 0w-20. Since I believe it is important to stick with manufacturer recommendations I won't use a heavier viscosity oil, especially with a new turbo. I buy Subaru filters by the case so I will continue with them. I also will install a Fumoto drain plug. As far a how many miles between changes, I'll try and make the first change at 3,000 and every 5.000 after that if the oil remains clear. Thanks, that's my plan and I always like a man with a plan.
Fumoto drain plugs are awesome! I have one on my Xterra and that will be the first modification to the car! Makes this a clean oil change with zero oil on the floor and can drain it right into a container for disposal.

With the top filter this will be a really easy car to change oil on!
 

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I believe that a high detergent gasoline will not help with carbon deposits in the intake manifold or on the intake valve stems. In a DI engine the fuel is injected directly in to the combustion chamber... Two inches further along in the combustion process. It does not provide a flushing mechanism in the intake manifold.

The carbon that builds up is a combination of exhaust gas injection from the EGR valve, oil droplets, crankcase vapors from ring blowby through the PCV valve and any oil leakage from the turbo shaft seals.

A high detergent fuel would help the combustion chamber, piston crown and exhaust valves, also the fuel pump and injectors.
 

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I believe that a high detergent gasoline will not help with carbon deposits in the intake manifold or on the intake valve stems. In a DI engine the fuel is injected directly in to the combustion chamber... Two inches further along in the combustion process. It does not provide a flushing mechanism in the intake manifold.

The carbon that builds up is a combination of exhaust gas injection from the EGR valve, oil droplets, crankcase vapors from ring blowby through the PCV valve and any oil leakage from the turbo shaft seals.

A high detergent fuel would help the combustion chamber, piston crown and exhaust valves, also the fuel pump and injectors.
To your point reading the oil spec stuff on the oil side for many yrs now it has been the oil thats been required to have certain properties to reduce crud build up not fuel again to your point in how modern engines deliver fuel. The most important aspect today seems to be oil quality and the correct viscosity. Oil quality goes hand in hand with its stability rating. The more stable the oil and its ability to carry impurities without having side effects like gumming things up in the areas oil will be blown as a fine mist etc.
 

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To your point reading the oil spec stuff on the oil side for many yrs now it has been the oil thats been required to have certain properties to reduce crud build up not fuel again to your point in how modern engines deliver fuel. The most important aspect today seems to be oil quality and the correct viscosity. Oil quality goes hand in hand with its stability rating. The more stable the oil and its ability to carry impurities without having side effects like gumming things up in the areas oil will be blown as a fine mist etc.
So is this why some people seemed somewhat surprised that Subaru went with a thinner,0w20 oil instead of a thicker 5w30 oil? Less chance of oil mist with the thicker oil? Or did I misunderstand.....very possible because I am not a Auto/mechanically inclined person...
 

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So is this why some people seemed somewhat surprised that Subaru went with a thinner,0w20 oil instead of a thicker 5w30 oil? Less chance of oil mist with the thicker oil? Or did I misunderstand.....very possible because I am not a Auto/mechanically inclined person...
Fair question. All auto makers are using what they refer to as friction reducing technology in modern engines which also have really tight tolerances between parts. The thinner oils play a part in this “reduced friction” aspect given it is a combination of things being done along with oil weights.
 

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I think the most important thing to understand is any time you change to a different brand 0weight oil you need to really watch for oil consumption and make sure you do not run it low. The range of quality/ stability in the 0weight oils brand to brand seem to vary widely. Also just the nature of these engines higher compression, lower friction surface treatments in the cylinders etc oil usage is going to be more common than the old engines of yester year. Meaning you do need to take a quick look at oil level every 1000 miles as a normal practice of owning these modern engines. Its just the nature of the beast.
 

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Fair question. All auto makers are using what they refer to as friction reducing technology in modern engines which also have really tight tolerances between parts. The thinner oils play a part in this “reduced friction” aspect given it is a combination of things being done along with oil weights.
Does/can a “thicker” oil like a 5w30 harm a engine that specifies a 0w20 oil? Or is it strictly about gas mileage.? Just thinking about the effect on the tighter tolerances...
 

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I have read that some engines not sure which ones can see odd oil issues where the heavier oils don’t coat parts as well. From what I have read I figure its a little of both there may be some mileage benefits of the 0weights and pending the engine there may be some design aspects that do better with the 0 weights.

Though one thing is for sure!! There seems to be a huge range of oil quality between brands that really impact the oil usage. I had lots of issues with my 2005 Sequoia having high oil consumption with Mobile 1 and essentially zero with Chevron oils. Same with with our VW. My 05 Mercedes which has Mobile 1 only stickers plastered all over under the hood gets Some fancy stuff my local german shop uses and they say no to using the Mobile 1 now.

Many other Forums subaru, ford, toyota etc all have very similar threads discussing the wide range of oil quality from brand to brand especially with the 0w oils. So more than anything just being in the habit of checking oil levels regularly is just the smart thing to do.
 

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Oils contain friction modifiers, viscosity modifiers, detergents to keep contaminants in suspension to prevent sludge, manage corrosion and moisture and some metallic compounds to coat surfaces for high pressure contact areas (like rings on the piston walls and the lobes on cams).

It is all of these additives that wear out and get used up as oil accumulates engine hours. Additionally combustion gases add carbon to oils and fuel residues thin out the oil, lowering viscosity and flash-point.

If you have ever had oil sent out to a lab you can ask for a TBN (total base number) that tells you how much life an oil had left. Higher quality oils start with a high TBN number and as they wear out there is.more residual life in the oil. Some new oils have a poor TBN right out of the bottle and are well below minimal TBN numbers at 5000 miles. There are references on TBN for almost every major oil out there.

Note that you can't just say "I run mobil1" or "Castro synthetic"... There are about a half dozen sub types for most major brand; some great, some not so good.
 
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