oil drain interval-sever vs normal service

ejp said:

I have 6 mo but only 2500 mi on 5 qts of Mobil-1 (5/30). The 2008 Subaru Outback 2.5i 4 cyl w AT is driven daily on city streets and 4 hrs at interstate speeds (70-80mph) every 60 days. The local driving is in 20-30 min range at stop and go speeds. Temps are central Cal moderate, but very hot in summer.

Is this severe enough service to warrant changing synthetic oil by the calendar vs actual mileage? It somehow seems nuts to change at 2500 mi when the factory says 7500, especially with synthetic.

Thanks for your comments.

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Over time oil absorbs all sorts of things and after a while can't keep that stuff suspended. I'm in CA and we do lots of Central valley hot trips during the summers. Which case during the summer I generally change it at around 4500 to 5000 miles pending if we are hauling trailers etc.

Regarding time vs miles 6 months for a single change is a drop in the bucket regarding vehicle cost yes change the oil. We have a large SUV the family 3rd car which sees about 6000 miles a year I try to change the oil no later than 6 months usually around 5 months. Synthetic is better at staying stable and clean that long but some would argue that the impurities sitting in the oil that long could cause issues with gaskets and seals.

I wouldn't go more than 6 months and during the hot dusty summer months no more than the 3-4 month time frame. Central valley is hard on oil due to the heat and lots of dust.

With most of your trips lasting longer than 20 minutes you don't have to worry about condensate contamination, so it's just dust aspiration that you have to worry about.

In your shoes I'd leave the oil in there all year and change air filters twice a year.

Drain Intervals

I will be picking up my '13 3.6 in about four weeks unless somebody tells me the CVT tranny will be available in the 2014 model for the 3.6 engine.
Here are the drain interval options using AMSOIL synthetic:

1. Use the Amsoil OEM and change at manufacturer's recommendation.
2. Use Amsoil XL and change twice a year.
3. Use the Signature Series and change once per year, but change filter 2x*

* Since I live in California (land of the EPA and all fuel formulated in-state), I will be using the top-of-the-line Signature Series and probably changing 2x per year because I put right at 32,000 miles per year on a vehicle.

Best,

Thanks all for your inputs. Since it's synthetic, I think I'll run with it a bit longer.

Ejp,

I'm an experienced Amsoil dealer and I'd feel comfortable running Mobil 1/EP for a full year under those conditions. If its really dusty you might consider changing your air filter every 15,000-20,000 miles. However every time you open the air filter housing and mess with the intake plumbing there's a chance of introducing dirt into the system. In addition the efficiency of air filters actually goes up significantly once they get a bit dirty and the larger pores become partially plugged with debris. So I wouldn't be over zealous with air filter changes.

If you had a real concern you could have the oil analyzed for $25.00. It's a good idea to do this with Subaru's under warranty, since they've had a history of coolant leaks at the cylinder head gaskets. You can catch these very early on through oil analysis, by looking for trace elements found in coolant.

TS

IMO, the oil information in the owner's manual leaves a lot to be desired.
Things like you should stick with synthetic if you switch to it (1980's logic), 5W-40 conventional can be used for replenishment only (in vehicles that spec 0W-20/5W-30) and no such oil exists.

I think it comes down to how much of a hard time that the dealer will give you over any potential warranty concerns and how much of a fight you're willing to put up if you need to. My dealer definitely would not give me any hassle if I changed annually and only did 7,500 miles in a year.

OTOH, I've seen silly things like a dealer trying to blame a misfire code on the use of 5W-40 oil in a WRX (one model year after SoA dropped 5W-40 from the owner's manual on the same engine). They drained the 5W-40, put in 5W-30, and charged the guy $100. One week later his CEL came back.

How many dealers would change the oil in a car that sat on the lot for 8 months prior to selling it?

-Dennis

TooSlick said:

Ejp,

I'd feel comfortable running Mobil 1/EP for a full year under those conditions.

TS

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What is the main difference between Mobil 1 Extended Pour and their regular Advance Formula?

Does one have more PAO or Group IV in it than the other or do both use the same basestock with different additive packages?

The Mobil 1, Extended Performance has higher levels of detergent/dispersant additives, with a TBN of approx 9.5, vs 8.0 for the regular Mobil 1. Physical properties data are extremely close, so I'd say the base oil blend is the same. Mobil has been making heavy use of their "VISOM", Group 3 base oil in a number of their Mobil 1 formulations. This looks to be the major base oil in this case.

TS

I would follow the Manufacturers recommendations regarding oil and filter change intervals, these are not an arbitrary number, they are based on engineering requirements including Operating teperatures, fuels used, climate/regions. I have changed oil on Honda Civic GX's (CNG Powered) at 10,000 Miles (recommended) and asked myself why was I doing this since the Oil looks fresh as the day it was poured in the engine, and Diesel engines that the Oil is Jet Black at 3K.
I would be careful using some of the Amsoil products as they didn't used to have an API rating, and can Void your warranty. Every Manufacturer requires API rated Oil fluids, I suggest sticking with them.

Joe,

The Amsoil OE and XL product lines are API licensed, as is their 5w-40, Premium Synthetic Gas/Diesel Oil (Product Code DEO), which meets the latest API/SN rating. If you have any technical and/or applications questions about Amsoil, please contact me off line. I work as an aerospace engineer and have been a registered Amsoil dealer since 1980.

Sincerely,

Ted