Oil Recommendation: 1999 Subaru

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Oil recommendation format as stated in the sticky thread. 1. What kind of vehicle you have A 1999 Subaru Legacy Outback Limited wagon, 5-speed manual. Engine and car currently have about 107,000 miles. 2. What your owner's manual says -- not just viscosity, but certifications (look for acronyms like API SM, ILSAC GF-4, etc.) and change intervals as well 5W-30 and 10W-30/10W-40 viscosities recommended. Severe duty oil viscosities listed are: 30, 40, 10W-50, 20W-40, 20W-50 Pretty sure that API SJ/SH is outdated/obsolete now so I'm sure an API SM will do the job fine. OCI is about 3,700 severe service (such as short trips, stop-and-go, etc), so I'll religiously go by that (or shorter). The 7,000 mile-ish OCI only applies to easy driving (such as freeway driving), so that's mostly irrelevant. 3. Where you live San Francisco Bay Area (NOT in SF itself, around the San Jose area). I do intend to adventure around California once in a while though. As for stop-and-go, we got a good amount of that as well. 4. How you drive (easy? hard? fast? slow?) With the engine still cold and not up to operating temperature, I drive very easy. Then I drive "normal", moderately easy until engine warms up to a good operating temperature where high-revs are allowed. I typically drive moderately fast (legal-type of fast), then bursts of very heavy driving/acceleration. Sometimes I do drive slow, but for the most part, I accelerate to the engine's full potential where it may be necessary (such as merging onto freeways) Driving near redline is an addiction I try to suppress (but I try not to hit the rev limiter). Also, once in a while I have off-road excursions. 5. What your daily drive is like (short trips? long trips? city? highway?) For now, mostly short trips that by the time I get to my destination, the temp gauge reads around the middle, safe for high-revs. Medium-length trips around town occur moderately (meaning about 20 min driving minimum). 6. Whether your car has any known problems The EJ25D Phase I has been known to blow head gaskets badly. Thankfully for me, I check under my hood quite often and caught the problem immediately, and got it fixed. It happened around 85,000 miles. Also, this engine is known to have moderate to pretty bad piston slap, almost sounds like a diesel engine in the colder months! I've heard using a thicker oil might cure it, but I'm not sure. As of now, intend to run 5W-30 for colder months, 10W-30 for warmer months. I'm considering the severe duty oils listed since I "drive it like I stole it", but am not sure since I do have a decent amount of short-trips. And I do have a brand bias. I would prefer Castrol or Chevron/Texaco products (don't ask why, it won't make sense), but curious as to what you experts here at BITOG have to say.
 
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use the 5w30 all year and you wont have any oil related problems...Head gaskets are another thing with those engines.. we see a lot of them in my engine shop with head gasket issues not as bad as the chrysler 2.7 or the ford 3.8
 
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San Jose is not hot in summer, you can use 5W30 all year long. Chevron Supreme is a good oil and Pennzoil Yellow Box is also a good oil for 4k miles oil change interval too. Actually, any brand name convention SM or the new SN with work great for 4k miles OCI. Just buy whichever that costs less, specially when you can buy it on sale.
 

AWDfreak

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Originally Posted By: HTSS_TR
San Jose is not hot in summer, you can use 5W30 all year long. Chevron Supreme is a good oil and Pennzoil Yellow Box is also a good oil for 4k miles oil change interval too. Actually, any brand name convention SM or the new SN with work great for 4k miles OCI. Just buy whichever that costs less, specially when you can buy it on sale.
So long trips around the desert aren't a problem with 5W-30? And there are rare times when the ambient temperature could exceed 100 degrees Fahrenheit over here, which is the ambient temperature range that the owners manual recommends 10W-30. Even with that taken into consideration, I can still run 5W-30??? The 10W-xx viscosity would only apply for a cold start but I've heard Subarus like thicker oils.
 
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Ive owned over 6 subarus. They typ dont like or want 5w-30 oils. 3 litres Rotella T 10w-30 with 1qt Formula Shell 5w-30 works well. Also 50/50 MC5000 10w-40 and 5w-30 works well. Our last one (in sig) came with a "rod knock" from the factory so we are just waiting for it to die. I though the PYB SN 5w-30 might hasten its demise wink I do not like Havoline or Castrol in this application. Havoline is a good oil, but the 5w-30 is WAY to thin - its pretty much the thinnest multigrade 30 on the market.
 
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Originally Posted By: ARCOgraphite
Ive owned over 6 subarus. They typ dont like or want 5w-30 oils. 3 litres Rotella T 10w-30 with 1qt Formula Shell 5w-30 works well. Also 50/50 MC5000 10w-40 and 5w-30 works well. Our last one (in sig) came with a "rod knock" from the factory so we are just waiting for it to die. I though the PYB SN 5w-30 might hasten its demise wink I do not like Havoline or Castrol in this application. Havoline is a good oil, but the 5w-30 is WAY to thin - its pretty much the thinnest multigrade 30 on the market.
+1. My Subie had 10W-40 and loved it. My massive displacement Nissan Inline 4 did too. Both of these engines tend to "Die" on too thin Oil. Its the way they are. Well maybe not "Die" but "Wear out so fast due to oil too think that its the same as dying." My Subie was a 1996 Outback wagon, 2.5L H-6. Not all that different from your 99.. though even if you got the 3.0L H-6 (GREAT Engine man its near the top of my list for engines i like the best and i buy cars over the powerplant and look, straight up) then that means your engine needs 10W-40 even more than mine did.
 
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MaxLife 10w-30 or 10w-40 would be great for this application, as would Shell Rotella T5 10w-30...both relatively inexpensive but robust. My Legacy has a similar engine (Phase II EJ25 SOHC), and is running strong on a long diet of MaxLife and HDEOs before switching to Pennzoil Ultra. Zero detectable piston slap, but the valved do need to be adjusted.
 
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I would run a High Mileage oil such as Max Life, GTX HM, or Pennzoil HM. I've been running HM oils in a '00 RS and '99 OB for several years with no problems and minimal consumption at 5-6k intervals (less than 1 qt. between the two cars). If you look at the data sheets on High Mileage oils, you'll see that their viscosity is on the high end of their respective grades. They also usually have higher levels of detergents and Anti-Wear additives along with additional seal swellers. Nothing could cure the Genuine Subaru Piston Slap in my wife's Outback. I tried everything from thick to thin, conventional, synthetic blends, and synthetic. 5W-30, 10W-30, 5W-40, and 10W-40. OEM oil filter, Purolator oil filter, etc. Did a couple of uoa's on it and they always came back very good. Even with a conventional HM oil, you can probably go closer to the normal service interval of 7,500 miles, IMO. N/A Subaru's are easy on oil. drive -Dennis
 
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I've had a ton of subarus, and there's many others in my family.. we got EJ18, two EJ20 turbos, EJ22, many EJ25s, and 3 EJ25 turbos.. The turbo ones you are fine with 5w30 but if you drive hard and it's hot.. maybe 0w40 or 5w40 is better usually, specially after high miles. The non-turbo ones see nothing but 5w30 synthetic, and during the winter they see 0w20.. they do not complain. Many of them have over 300k+ miles, just keep up the maintenance, timing belts, and don't forget to also change the transmission fluid and gear oil for BOTH diffs.
 

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Update. Did the oil change. Oil filter is still the Subaru Honeywell OEM filter (but obviously a new one) But I decided to run with 5 quarts Castrol GTX High Mileage 10W-40. I tried to take all of your experienced Subaru owners/drivers experience into account. When I drained my oil, there was an alarmingly small amount of oil that drained out, about a U.S. gallon of 3,700 mile motor-oil came out. That has me a bit concerned how low it is (the capacity is 4.7 U.S. quarts), since I do drive it hard. On start up, I could immediately tell the 10W-40 is a MUCH BETTER viscosity. During a cold idle, the piston slap is SIGNIFICANTLY reduced to the point where it is hardly noticeable. And once I got the engine warmed up to a good operating temperature for hard acceleration, it feels like the engine has slightly more torque than before (during WOT in high RPMs). Yeah, 5W-30 was perhaps too thin for this high amount of mileage. I feel that I should probably resort to the "severe duty" listed viscosities on my next oil change since I pretty much do WOT in merging all the time. Yay or nay? Fuel efficiency isn't too important to me. MrWideTires, what is the mileage/time interval for the differential oils???
 
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Originally Posted By: AWDfreak
I feel that I should probably resort to the "severe duty" listed viscosities on my next oil change since I pretty much do WOT in merging all the time. Yay or nay? Fuel efficiency isn't too important to me.
Based on experimenting with many different viscosities in my wife's '99 OB, the severe duty viscosities are not needed IMO. Even when I snuck in the 10W-40, my wife told me that her car felt more sluggish when trying to go up hill. The 30 grade HM oils are in the upper 30 range at 12.0 and 12.1 cst's at 100c (close to a 40 grade). Castrol product data sheet. -Dennis
 
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Considering you drained out less oil than it should been filled and you are comparing old oil to new. I seriously doubt the viscosity of oil did anything to change the piston slap issue. Piston slap will still be there regardless of oil viscosity however certain oils tend to dampen sound better. I believe that is what you experienced. Considering you are in a warmer climate, there is nothing wrong with using a 10w30 oil but don't think a 5w30 would do you any harm as well. Subaru's don't die on a thinner oil, they die from be broken from the factory. They can, will, & want to run on 5w30 just like it was anything else. The question is can the owner stand up to the challenge of letting in there? 1200 miles on AFE and I am happy to report I am happy!
 
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