Oil change frequency - H6 Outback(s)

[craigmcd]

Hi All.

 

Simple inquiry. Our 2005 and 2012 Outbacks each have the 6 cylinder engine. Each car is over 100,000 miles. I use the Valvoline high mileage synthetic blend motor oil, 5W-30. One reason I use this is because I can run the exact same oil in our 1995 Chevy van - so I only have to stock one kind of oil in the garage. I can also purchase it easily nationwide. My wife puts a lot of highway miles on the 2012, but the 2005 only does about 8-10K per year.

 

So, how often would you change oil ?

 

Thanks for the ideas. C

[Numbchux]

Subaru recommends conventional oil on the H6s, different resources conflict whether it's 6k or 7500 miles.

 

The research I've seen (there was a report by Blackstone labs last fall that was very interesting on the subject), that the age of the oil matters much more than the type of oil, when it comes to wear. I run the cheapest oil I can find, and change it at or before the recommended interval. I shoot for about 7k on our '04 Outback H6

[craigmcd]

Thanks for the input. I notice you have a Brat. There are a couple nice ones in our area. I would love to have one sometime. C

[GeneralDisorder]

Subaru is in the business of selling (new) cars. Oil companies would love to sell more oil. 

 

Full synthetic ("high mileage" is bull$hit), WIX filters (better than the Honeywell/Fram SOA filters) and 6,000 mile changes. You can go more depending on the oil and if you change the filter/top off as needed. 

 

As an engine builder I can tell you EMPHATICALLY - you will wreck the engine and get half it's life with conventional and the recommended intervals. None of the common filters are good for more than 5k miles. 

 

GD

Edited May 18, 2018 by GeneralDisorder

[idosubaru]

Change it frequently and you’re golden. If I was driving that low miles I’d change it spring and fall so I’m not changing it in the filthy nasty undercar winter. Haha.

 

I choose every 5,000 miles on the odometer on the even 5k and 10k so 200k, 205k, 210k, 215k...etc. just because it’s easy. Pick what’s easy for you - calendar, mileage, etc.

 

You’re better off using full synthetic, or conventional, but I get it and it really doesn’t matter. The blends are probably market driven products and enough synthetic to sell and line pockets. Either way - Might as well get real synthetic for best product available or conventional and save the cash change it frequently.

 

If you’re worried about it - have an oil analysis done and they’ll tell you how often to change it for each vehicle.

 

GD sees lots of subarus daily no doubt some that get low or overheated have unknown history so he knows what happens when they fail. I’ve got 200, 200, 226, and 285k on my current Subaru H6s with the cheapest on sale conventional oil as well just like numbchux. If it’s not abused overheated or run low on oil then in my experience they do great as average daily drivers.

[jp98]

No matter what kind of oil you are running get yourself a sample kit from Blackstone Labs or another company that will analyze it..  Get a sample and then send it into them.  They will then send you a complete breakdown of what is in the oil and if you can go longer or if you need to change it more often. 

[craigmcd]

So what I am getting from all this expert advice is this.  Change the oil every 5,000 to 6,000.  Use a quality filter (I always use a geniune Subaru oil filter replaced with the oil change).  Use either a full synthetic, or a conventional oil - which Subaru recommends for the H6.  GD is EMPHATICALLY against conventional motor oil. You guys seem to be saying that the synthetic blend is more of a marketing thing, and not worth the money (they are $32 / 5 quarts).  I will probably skip the lab work, seems like overkill for normal driving.   Thanks for the input, I appreciate it.

[idosubaru]

I’m not saying for sure the blends are pointless and my comment may not be accurate, I’m sure you can search or ask and find data on it. but personally I wouldn’t ride the fence, either use actually great oil (synthetic) or lower cost conventional with great change intervals/checking oil level.

 

In general I’d run synthetic unless the car is using/leaking oil and cost to top it off is annoying. Beyond that synthetic gets you longer change intervals so it doesn’t really cost more and saves time - fewer changes, fewer trips and purchases to manage and less oil to store/manage/recycle and a better end product. Conventional can be fine just don’t go over mileage, overheat, or let the level get low. But never use it in a Subaru turbo.

Edited May 19, 2018 by idosubaru

[GeneralDisorder]

Synthetic makes a difference. I have 320k on a 1990 Legacy 2.2. Not only does it run, it runs PERFECT, and when I replaced the head gaskets at 286k you could serve up dinner with the valve covers. It uses NOT A DROP of oil. And my Amsoil rep has 470k on an old Jetta. Can you get 250k out of an engine running conventional? Yes. But that same engine may last twice as long or 4x as long if it had synthetic. You can also double or triple (with filter change halfway) your oil change interval. This saves time, resources, and replacing engines. With bypass filtration, filter changes, and top offs you could pretty much go indefinitely without changing it. The big rigs do. Many will run 500k without an actual oil change. Just filter, bypass filter, and top off. The oil will not break down. It will shear down to a lower viscosity and you will need to replenish the additives but otherwise it never wears out or breaks down.

 

Why you wouldn't use this amazing technology is beyond me. It's about the same price (or cheaper if you count your time) if you take full advantage of its abilities.

 

GD

[matt167]

 the new sku's of Walmart Supertech synthetic is now GM DEXOS certified. Making it as good as any other synthetic but saving about $10. I generally don't run Walmart oil BUT, with an OEM certification I just might..

[idosubaru]

GD yeah man I totally agreee. if it’s not using/leaking there’s no reason not too, the time savings, benefits, cost make it no contest.

 

not everyone is going to so maybe quantified/qualified approaches with archaic fluids have a place for discussion even if it is learned helplessness or ignorance. Haha

Edited May 20, 2018 by idosubaru

[GeneralDisorder]

I can understand if the engine already burns or leaks such a large quantity its not practicable. Or in the cases where the body is so rusted out by 200k it doesn't matter how the car runs its still scrap. Ok I can see that.

 

But if you start from a solid foundation - and do rust prevention, proper maintenance, etc - there's no real reason you can't get the benefits of synthetic for essentially free if you value your time and do the required math to scale up the intervals. Investing in bypass filtration further increases the savings and will pay for itself.

 

Many fleets have come to this conclusion. Scheduled maintenance and unscheduled downtime is expensive labor when you paying equipment operators to sit around while their truck is being serviced.

 

GD

[Bushwick]

^Semis rarely go above 2k rpms, have giant sumps and oil capacity can be 18-44~ quarts depending on the engine. But going 500k miles with contaminated oil on a $10k-$20k+ TURBOCHARGED engine (not including labor/shop charges) is beyond foolish. That's at least 4-5 years (@100k/per year) of god only knows climates. When I drove, 30k mile drains were common IIRC as that was cheaper than replacing the engine they were looking at getting 1 million miles out of before selling the trucks off. http://www.machinerylubrication.com/Read/29117/oil-change-intervals

 

Full synthetic in gas engines is definitely the way to go. You spend WAY more per year on gasoline fluctuations than you'll ever spend on oil (not even doing the math on that, pure guessing) but yet people want to go cheap on the oil to save $5-$10 a year or go really long w/o changing it? Why risk it? If the oil is getting black early and wreaks of gasoline, change as needed. Environment, driving styles, traffic you face, etc. can all shorten oil life.

 

A funny story about "how long you can go w/o changing oil" I just remembered. In '84, my mom and step dad bought her first new car. An '84 Ford Escort (US) base model (no A/C, no FM stereo, 4 speed, vinyl everywhere, no power anything) and they put roughly 55k miles on it by 1988. While going through their divorce, it started burning oil, badly. I remember the vents (just blowing air or heat, no AC) would pump burning oil smells into the cabin (no idea how, just that smell was horrid). My mom had her dad get check it out. Turns out, my step dad, who wasn't a car guy and knew virtually nothing about cars, had never changed the oil- EVER. So 55k miles w/o an oil change, on conventional 80's garbage oil on a throw away ford engine   It's doable....

Edited May 21, 2018 by Bushwick

[GeneralDisorder]

^Semis rarely go above 2k rpms, have giant sumps and oil capacity can be 18-44~ quarts depending on the engine. But going 500k miles with contaminated oil on a $10k-$20k+ TURBOCHARGED engine (not including labor/shop charges) is beyond foolish. That's at least 4-5 years (@100k/per year) of god only knows climates. When I drove, 30k mile drains were common IIRC as that was cheaper than replacing the engine they were looking at getting 1 million miles out of before selling the trucks off. http://www.machinerylubrication.com/Read/29117/oil-change-intervals.

 

It is done quite often with Amsoil fleet's. They use 1 micron bypass filtration - it even removes the carbon so the oil doesn't turn black. 

 

https://www.amsoil.com/shop/by-product/filters-and-by-pass-systems/by-pass/filters-and-mounts/universal-single-remote-bypass-system/?code=BMK21-EA

 

And yes they have large sump capacities, and HUGE filters. When you change the filters and do the top off you are adding several gallons of oil (and therefore additives) back into the system. This is what allows the extreme change intervals. Most of them also do oil analysis to back it up with actual data. 

 

In the Army we didn't change oil unless the analysis said to do so. The Army runs it's own Army Oil Analysis Program (AOAP) for just this purpose. 

 

You are right that this isn't usually feasible in gas engines due to gasoline contamination. Diesel fuel isn't as problematic in this respect having a high lubricity itself. 

 

GD

Edited May 21, 2018 by GeneralDisorder

[craigmcd]

GD, you have mentioned bypass filtration a couple of times. I don't believe I have heard of that before. On the H6 engines, how does that work, and where is the mode done on the engine ?

 

Otherwise, thanks all for the interesting conversations, I will look at converting the Subarus to synthetic. The 2012 does use a little bit of oil, but the 2005 is like a corked bottle. My 1995 Chevy van is the aforementioned rust bucket, so I will keep it cheap.

[carfreak85]

I literally write the service documentation for commercial diesel engines used in big rigs.

 

The recommended oil change interval for our engines is 30-75,000 miles, depending on duty cycle (vocational is 30k mi, line haul is 75k mi).  We specifically DO NOT allow supplemental oil additives, we do not allow "top offs," as long as you want to maintain your factory powertrain warranty.

[Subaru Scott]

GD, you have mentioned bypass filtration a couple of times. I don't believe I have heard of that before. On the H6 engines, how does that work, and where is the mode done on the engine ?

 

Otherwise, thanks all for the interesting conversations, I will look at converting the Subarus to synthetic. The 2012 does use a little bit of oil, but the 2005 is like a corked bottle. My 1995 Chevy van is the aforementioned rust bucket, so I will keep it cheap.

 

Look up "toilet paper filters," been around a long time.

 

Really only beneficial for big rigs with gallons of oil, but I have known some very, (ahem) "frugal" individuals who have installed them on cars and pickups.

[DaveT]

Look up Amsoil bypass filters.

I have been running with them since the 80s.

[matt167]

No real need for expensive stuff if you want to bypass. Wix 24755 filter mount and a Wix 51050 bypass filter.. Pressure off the engine, and drop it back ( filtered ) to the pan.. You can use a sandwich adapter if you chose or just Tee under the alternator at the pressure switch.

[craigmcd]

Thanks guys for the info on the bypass filters - I will do some more research. New topic for me.

 

Happy Memorial Day !