Subaru Outback Oil Consumption... Without a Trace

[bawalker]

Just a quick update. I got my oil change last week and went with Penzoil high mileage, non-synthetic oils since others on here suggested synthetics are thinner oils? Anyway I couldn't find a 10W40 RotellaT6 so Pennzoil seemed to be an alternate good choice. I went with MMO and so far the oil is holding steady.

Also the day afterwards I changed my PCV valve which was pretty oiled up and not moving as smooth as the new one was. I also went with adding 6oz of MMO to my 16gallons of fuel fill up the day after the oil change too.

It won't be for another few days as I'm checking my oil once a week to see if I notice consumption levels. But in the short term I have got some smoother idling and a hair few more HP back in terms of pep in my engine with MMO in the gas.

I'm really hoping that I'll notice a major decrease in oil consumption within a few weeks. If I go from 1qt ever 1k to 2k+ then I'll consider that a major win and that the rings were gunked up.

Does anyone have any advice on should I run MMO again on the next oil change? Any advice on changing weights of oil next time too? Or is this MMO par for the course every change or every few changes?

 

[meep]

Originally Posted By: Drew99GT
Originally Posted By: meep

all good advice above. I would suggest all as good:
- compression check - may educate you more to the problem
- rotella, MMO, Kreen, --- a regular dose of cleaners just in case it's stuck oil rings.
- use the thick oils, like they've said. HM, rotella, etc. BUT, include a third-to-half quart of 5-20 synthetic. THAT combo did things I still do not understand when I was running a 240,000 jeep I6.


Sorry to hijack the OP thread, but could you briefly elaborate meep? Did the above fix any oil consumption problems you had in your Jeep?


Sorry for the delay-- hadn't been back in a bit--

YES. but let me clarify. I played with HM oil, which slightly slowed the jeep's consumption initially, just being a grade thicker. I ran a lot of MMO, constantly, for probably 6 months. There was a pretty loud valve racket that would oddly /shut up/ if I added 1/3-1/2 qt of 5-20syn. This engine was fed scrap oil of whatevr was on sale or laying around, so it saw many different types, but nothing addressed the tap like a splash of 5-20.

So.... what I settled on was this:

3 months of a lot of HM oil and lots MMO.
extra dose of MMO with top-offs and prior to oil change
started adding in a splash of 5-20

probably at 3 months got tired of spending as much on HM oil. went to half HM oil and half rotella 15-40. and a splash of 5-20. reduced use of MMO but still kept some in the sump.

I gradually weened off the MMO, and stayed with a HM/rotella/5-20 diet. It went from a quart per week to maybe a quart every ~2.5, maybe 3 weeks. pretty dramatic. None was from the main seals--- they were reasonably dry--no dripping. Some was at the cylinder head, there was even weeping on the outside... I overtorqued all head bolts/studs by 20 ft/lbs (some were 30 under) and that helped a number of things, including coolant loss. Mine was a basket case, but I had more fun with that basket case than any other vehicle, ever. I missed it often until years later when I found the tundra, which for some reason speaks to me with a similar "soul" the ZJ had.

 

[bawalker]

Just a quick update. I'm approaching my first 1000 miles after the oil change and so far no oil consumption!! It's been about two weeks now and as of this afternoon the dip stick is still on full.

I've made sure to check it after the engine is cold and the oil has settled each time for consistent results.

I did have to top off the oil after I brought it back the other week because the mechanic forgot to add the MMO and had to drain some oil and then add the MMO in. It was 1/3 of the way down the dipstick, but since I topped it off then, so far it's held steady.

I'm getting encouraged!

 

[Hollow]

Having had 2 different Subaru's now, both of them started consuming oil like crazy when the PCV clogged up. Both typically consume about half a quart every 5000 miles, and always have. Was 1.5 quarts low with a clogged PCV.


Always a good place to start, in my opinion. Glad to see your consumption might be improving.

 

[KitaCam]

Originally Posted By: Hollow
Having had 2 different Subaru's now, both of them started consuming oil like crazy when the PCV clogged up. Both typically consume about half a quart every 5000 miles, and always have. Was 1.5 quarts low with a clogged PCV.


Always a good place to start, in my opinion. Glad to see your consumption might be improving.


With clean PCV valve it consumed 1/2 qt per 5k miles...? That's great....

 

[gomes512]

Glad to hear the oil level is holding steady for now. However, did you check the PCV system carefully. Most people look at the valve and associated tubing but fail to check the ports that the valve and tubing plug into.

I use a flashlight to check the ports in the valve cover and intake manifold thoroughly. The last Corolla I worked on had a clogged port on the intake side. Owner thought it was valve stem seals since he had just changed the PCV valve and tube without change (2qts per 1K).

Might be worth a shot if your consumption issue comes back.

 

[Hollow]

Originally Posted By: KitaCam
Originally Posted By: Hollow
Having had 2 different Subaru's now, both of them started consuming oil like crazy when the PCV clogged up. Both typically consume about half a quart every 5000 miles, and always have. Was 1.5 quarts low with a clogged PCV.


Always a good place to start, in my opinion. Glad to see your consumption might be improving.


With clean PCV valve it consumed 1/2 qt per 5k miles...? That's great....


I think it is fine. Internal combustion engines use oil. 1/2 quart in 5000 miles is a negligible amount. Out of every vehicle I have ever maintained, they have all used 1/4 to 1/2 quart (sometimes more) per every 5000 miles. Foreign and domestic, new and 150,000+ miles.

I do not understand if you are being sarcastic or not.

 

[bawalker]

My previous post was premature. When I hit the 1000 mile mark I checked my oil making sure the car was level, not yet turned on that day, etc. I was down 1/2qt per the first 1000 miles in this current oil change.

I did notice already that the oil was becoming non-translucent with a darker color already at this point. Not sure if that is sludge becoming dislodged or...?

1/2 qt per the first 1000 miles seems to be significantly slower of consumption than previously, but now onto the second 1000 miles to see what happens.