Engine oil for my 08 legacy GT Limited

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10
Location
Washington
So I am in search or peoples personal data on what oils have worked best in their Subaru legacy gt limited with the EJ25 turbo engine oil life for mine on the factory subaru fluid was verry short so I switched It to 5-30w royal purple high performance oil for 1,200 miles got a better mpg of 1.5 -2.3mpg during that oil change then I was curious about the eneos performance oil so I changed my oil and put 5-30w eneos. Oil in and drive on it in same driving conditions as I did on the other oils same routs to work and everything and gaind another 2-3 mpg highway and city my maximum mpg with city and highway combined was 30mpg and a lowest of 20.3mpg So if you have logged data and seen improvements with other oils I have not tested I. My car what oil or oils did you use and what were your results my Subaru has only been tested on factory oil royal purple and eneos oils
 

gathermewool

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8,927
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New England
I'm going to say that the 10% increase in mileage is not attributable to the oil. The only way to prove otherwise would be to run back-to-back done runs with two or more different oils to determine fuel usage under near-constant conditions. When you say the Subaru oil life was very short what do you mean? In my '08 STI, Rotella T6 worked very well and was what I considered a very good bang for the buck. It's in my Forester now and I'm seeing up to 30 mpg in mixed driving.
 
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1,019
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Va
Running M1 TDT right now. Have run BC 0w-40, M1 0w-40, and PU 10w-30 over the last few years. There's a uoa of the PU on this board in my car. Consensus is run thicker than most 5w-30, and keep intervals below 5k. Personally I think T6 is overkill and with Wally jugs of M1 at current prices it is not the bargain it used to be. If your really modified, track, or live in a really hot climate, then T6 would make more sense. Look at some of the euro specs, which require hths 3.5+. There are some 30 grades that meet these specs. T5 would be the cheapest option at everyday prices. I'm only running TDT because I scored it on clearance. I don't track mpg. So I can't help you there. My on board mpg is skewed by my upgraded injectors. Be advised the computer mpg isn't perfect in stock form either. I've settled on any oil that meets Porsche A40, that I can get cheaply. That makes life easy feeding the Boxster once a year too. I ran the first 30k on castrol GTX 5w-30 because I was having the dealer change the oil. I had a good dealer and it was convenient. Then went to PP/PU 10w-30 for several years. Having done more research, I'm sticking with the Xw-40 crowd from here on out.
 
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147
Location
Ft. Collins
Fuel economy differences are heavily influenced by winds, speeds, acceleration, traffic variables. In controlled tests, there hasn't been more than about 2% difference between oils, not the huge swings reported here.
 
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3,870
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NEUS
I doubt very much there was a noticeable difference in 5w-30 oils. Anything you saw was more likely traffic patterns or weather. Use an oil appropriate for this turbo application and change at 5,000 miles with an OEM or Wix filter. Castrol Edge 0w-30 or 0w-40 Mobil 1 0w-40 or 5w-40 TDT Rotella T6 5w-40 Also: if you like Royal Purple, their HPS 10w-40 is good, or the Eneos 5w-40.
 
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17,301
Location
OH
Subaru turbo engines seem to do better on something thicker than the recommended 5W-30. M1 0W-40 is on rollback at many Walmarts for $22.46/jug. A known good oil that meets many demanding certs. There you go. Fuel economy in actual use won't vary much with oil choice either.
 

Jonlee89

Thread starter
Messages
10
Location
Washington
Ok so the stock Subaru oil was breaking down faster due to the heat of the turbo so I searched for oils that might withstand the heat a bit better I previously used royal purple in my other cars and had used some of their other products and they were great but I was still having the oil break down and leaving internals fairly dirty now I change my oil normaly ever 1,600-1,800 miles then I had been thinking about trying the eneos oil for a while and they remove some things from thier oil and replace it with other properties for their blend pack and it's designed to help keep the oil and engine cleaner and I drove on that and not only was it still clean and almost looking still brand new my engine ran smoother at idle then other oils and while driving the same roads useing cruse control keeping the car at as close to the same speed and rpm as possible there was gas mileage improvement regaurdless what others think on the stock Subaru oil my mpg was a low of 15.6 driving some what aggressively and a max mpg of 25 badly touching the gas every were I went not to impressive and I was surprised to see the change I. Mpg but it did in fact.
 

Jonlee89

Thread starter
Messages
10
Location
Washington
Part of that is true but you can get slightly better mpg and performance with oil now days with so manny company's changing oil to make it better and stay cleaner by removing some natural properties out and adding a additive that not only can bond to the internal parts better to protect better against metal to metal contact but withstand Heat better and help keep your engine cleaning thus extending the life of the engine
 

Jonlee89

Thread starter
Messages
10
Location
Washington
Ok thank you to everyone on your impute yes there aren't really going to be much change in the 5-30 oils but the perspiratory bled components that might be better then an other oils blend if it holds up to heat better and stays cleaner or wether it just bonds to the bearings and internals better and refuses the friction on internal parts
 

Jonlee89

Thread starter
Messages
10
Location
Washington
Ok so why Would the turbo setup run better on a thicker oil like say 10-30 or 10-40 vs the recommended 5-30 and what about the oil flow through the turbo lines and journal bearing passage in the turbo this is. My first Subaru and am just wanting to see what worked best for others in theirs with the same engine and turbo setup so I can see what oil might work best with this set up not trying to get better mpg I just want to know what seems to work best in the legacy gt what holds up to the heat and bonds well with the metal parts if It does get better mpg great
 

Jonlee89

Thread starter
Messages
10
Location
Washington
What oils would you recommend that can hold up to the heat of a turbo engine to help it stay cleaner and possibly reduce friction on parts and prolong life and why would you recommend them
 
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1,723
Location
Virginia
Originally Posted By: Jonlee89
Ok so the stock Subaru oil was breaking down faster due to the heat of the turbo so I searched for oils that might withstand the heat a bit better I previously used royal purple in my other cars and had used some of their other products and they were great but I was still having the oil break down and leaving internals fairly dirty now I change my oil normaly ever 1,600-1,800 miles then I had been thinking about trying the eneos oil for a while and they remove some things from thier oil and replace it with other properties for their blend pack and it's designed to help keep the oil and engine cleaner and I drove on that and not only was it still clean and almost looking still brand new my engine ran smoother at idle then other oils and while driving the same roads useing cruse control keeping the car at as close to the same speed and rpm as possible there was gas mileage improvement regaurdless what others think on the stock Subaru oil my mpg was a low of 15.6 driving some what aggressively and a max mpg of 25 badly touching the gas every were I went not to impressive and I was surprised to see the change I. Mpg but it did in fact.
Okay, couple of things. First of all, does your ISP charge you extra for using punctuation? Like is there a money saving thing going on with the absolute lack punctuation? The reason I ask is because if I was to ask a question that I wanted people to help me with, I would want to express it in a way that's easy for them to understand so that I could get a helpful/correct answer from them. However, I feel your writing style of no punctuation, and comments flowing into one another without transition, makes it difficult to understand. As for your comments, how do you know the stock Subaru oil was breaking down? How do you know that Royal Purple was breaking down and leaving the internals dirty? Changing your oil every 1,600-1,800 miles is overkill. It doesn't protect your oil any better, it wastes your time, and it wastes your money. Even Subaru doesn't suggest changing your oil under 3,750, so you can safely double your OCI. Using a quality Xw-30 or Xw-40 oil will protect your engine and turbo, and ensure you don't have an oil related issue for a long time; (gasket leaks are not a motor oil issue, they're a known occurrence on Subarus).
 

Jonlee89

Thread starter
Messages
10
Location
Washington
Ok plain boring question what oil/oils would you recommend. Why do you recommend it and what viscosity rating and why did you choose it over an other one.
 
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Messages
1,019
Location
Va
Please reread this thread. Several excellent oils have been suggested for your application. If you disagree with a recommendation, I'd suggest stating your reasons why you don't think it would be a good oil for your LeggyGT. If your only interested in a 5w-30 suggestion, I'd go with Pennzoil Ultra 5w-30. It seems to hold up, very little shear in use, better than most oils. Motul has a good rep as well. I'm not as familiar with the company product line up to suggest a specific oil.
 
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2,280
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SunnySouthFlorida
Originally Posted By: sicko
Originally Posted By: Jonlee89
Ok
As for your comments, how do you know the stock Subaru oil was breaking down? How do you know that Royal Purple was breaking down and leaving the internals dirty? Changing your oil every 1,600-1,800 miles is overkill. It doesn't protect your oil any better, it wastes your time, and it wastes your money. Even Subaru doesn't suggest changing your oil under 3,750, so you can safely double your OCI. Using a quality Xw-30 or Xw-40 oil will protect your engine and turbo, and ensure you don't have an oil related issue for a long time; (gasket leaks are not a motor oil issue, they're a known occurrence on Subarus).
....changing oil 4x more often than recommended cost more than any savings realized in MPG...
 
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Messages
3,870
Location
NEUS
Originally Posted By: Jonlee89
Ok plain boring question what oil/oils would you recommend. Why do you recommend it and what viscosity rating and why did you choose it over an other one.
Originally Posted By: Bandito440
I doubt very much there was a noticeable difference in 5w-30 oils. Anything you saw was more likely traffic patterns or weather. Use an oil appropriate for this turbo application and change at 5,000 miles with an OEM or Wix filter. Castrol Edge 0w-30 or 0w-40 Mobil 1 0w-40 or 5w-40 TDT Rotella T6 5w-40 Also: if you like Royal Purple, their HPS 10w-40 is good, or the Eneos 5w-40.
These oils are appropriately thick and have better addative packages. Pick whichever you prefer and run it for 5,000 miles. Send in a sample for used oil analysis then if you're concerned that it's breaking down.
 
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3,870
Location
NEUS
Also, one reading of miles per gallon on your car's dashboard is not an accurate way to judge changes in fuel economy. If you took data over several oil change intervals and compared different oils, you'll find that any difference in the oils you're comparing is statistically insignificant. That is to say, over 10,000 miles or more, you won't be able to tell the difference. Your posts are nearly impossible to read without punctuation and paragraphs. Please have someone proofread what you're writing before you post.
 
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1,019
Location
Va
Reference for motul 8100: http://www.bobistheoilguy.com/forums/ubbthreads.php/ubb/showflat/Number/3427790/gonew/1/Motul_5W30_8100_X-Clean_/_13'_#UNREAD Not the cheapest option by far.
 
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