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2015 FB25BC Touring w/CVT
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2015 2.5l with CVT

15K mi with ~5K mi. OCI's.

Driving conditions: 1-2 min warm-ups on cold starts, ~5min+ on those 'very' cold winter mornings while getting ice/snow off windshield, etc. 90% hwy/fwy, 10% town. Always up to OP temp on travels. No stop/go traffic in my neck of the woods. 87oct top tier/independent 30/70. Always add Bio-Plus fuel additive from RLI.

Sample 1: Factory fill and filter. Ran that analysis as more of a curiosity than anything else plus to get a base-line to how well things flush out in future UOA's.

Sample 2 and 3: Amsoil OE 0w-20 with EaO filter.s Noting the TBN on sample 2 being flagged, I added on an additional TAN this last sample.

I'd say almost flushed completely, still noting that pesky silicon number not dropping as fast as I hoped. TBN and TAN are quite close in relation to one another and explains why OAI flagged it. VOA on this oil for TBN is 7.9

Comments welcomed.
 

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2004 FXT / 2020 Outback Onyx XT
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1,679 Posts
Looks like high moly and ZDDP are showing back up in the factory fill after being MIA for a couple of years.

I wouldn't worry about the silicon. It takes a while to wash out. The Amsoil Ea filter is a good choice and I had my lowest Si numbers with it (lower than OEM). I wouldn't worry about TBN. You should be able to go the full 6k on this oil. Or switch to XL? Unless you plan to stick with 5k intervals then this oil is fine.
 

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2015 FB25BC Touring w/CVT
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Looks like high moly and ZDDP are showing back up in the factory fill after being MIA for a couple of years.

I wouldn't worry about the silicon. It takes a while to wash out. The Amsoil Ea filter is a good choice and I had my lowest Si numbers with it (lower than OEM). I wouldn't worry about TBN. You should be able to go the full 6k on this oil. Or switch to XL? Unless you plan to stick with 5k intervals then this oil is fine.
Thanks Blue for your assessment, appreciated.

Perhaps SOA had Idemitsu reformulate to help mitigate the oil consumption issue on some of these 2.5l during break-in. Just a guess. Perhaps upped the oil control ring tension as well, especially with this 0w-20 stuff. Doubt it but who knows. This 2.5l doesn't and never has used a drop of oil since we bought brand new, so we feel lucky we got a good FB25 on a 2015.

I'm sticking with 5k OCI's. It's easier for this old brain to remember 5, 10, 15, etc. I'm pleased with this OE oil with its price point. I have OE again in the sump and as the trend shows, hoping Si drops to <20 next analysis. First engine I've ever had where Si sticks around for so long to flush out. Interesting.

I'll probably go with XL next time that has a touch higher TBN formula if my TBN drops any lower than my average. I think there's a +/- 10% accuracy in TBN/TAN testing IIRC, even with ISO cert labs.

Am I on the right track or is my brain whacked in thinking you don't want your TBN lower than your TAN, or TAN higher than TBN? And if that were the case, your not controlling acid like the oil should and could start corrosion and sludging? This is the logic I always thought to be a good rule-of-thumb to go by. I'm in that condition IMO when I factor in the +/- 10% as worse case scenarios.

Opinions welcomed in general and on my TBN/TAN logic.
 

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2012 2.5X Premium M5 (sold)
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110 Posts
FB25 after short block install

Here's mine with 3650 miles after the short block install. I went with a shorter interval to get synchronized with the regular oil change schedule.

Oil: 3650 miles
Engine: 52 500 miles
Engine: FB25, 5-speed MT
 

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2000 Forester 4eat
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114 Posts
2000 Forester Oil Anylisis

This is the oil anylisis to my 2000 Forester at 263k miles. Only things done engine wise head gaskets at 125k, and head gaskets, piston rings, timing belt and 12 mm oil pump was done at 236k.

Oil used was Subaru Synthetic 5w30 oil filter used was the one that the dealer used. 6,450 miles on oil change
 

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2015 FB25BC Touring w/CVT
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2015 Forester 2.5 FB25BC engine @ 20Kmi. Amsoil OE 0w-20 used on smpl #2 ,3,and this most current #4 . Sample #1 was factory fill. Nice trend in the right direction. Sure took awhile to flush everything out, especially that pesky silicon. Amsoil's newest formulated 100% Synthetic XL 0w-20 in the sump now. See ya in another 5Kmi.

2015 Forester 11-9-17.jpg
 

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2019 Crosstrek 2018 XT
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14,712 Posts
This is the oil anylisis to my 2000 Forester at 263k miles. Only things done engine wise head gaskets at 125k, and head gaskets, piston rings, timing belt and 12 mm oil pump was done at 236k.

Oil used was Subaru Synthetic 5w30 oil filter used was the one that the dealer used. 6,450 miles on oil change
You could certainly go further. Just keep the oil level up near full.
When were the idlers, tensioner done?
 

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2000 Forester 4eat
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114 Posts
You could certainly go further. Just keep the oil level up near full.
When were the idlers, tensioner done?
yep idlers and tensioner was done. it was a gates kit and i am kinda kicking my self for just using the gates water pump instead of using a Subaru one. it works fine still. 6,400 miles is about the highest i will go on an oil change, just makes me a bit nervous. I will keep to the 6k interval.
 

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2015 2.5i Premium CVT
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451 Posts
2015 2.5L Latest oil analysis, 4402 miles on this sample, 16375 miles on the vehicle. Same type of driving on this sample as previous one: 90% short stop and go commutes, 10% highway. Now that I've had my curiosity met with results from a couple of analyses, with no issues as expected, I feel better doing oil/filter changes every 6 months, more just as a good excuse to crawl under the vehicle and keep an eye on things.

 

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2015 FB25BC Touring w/CVT
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2015 Forester 2.5 FB25BC @ 25Kmi.

Amsoil OE 0w-20 used on smpl #2 ,3 and #4 . Sample #1 factory fill. Sample 5 is most current using Amsoil's newest formulated 100% Synthetic XL 0w-20.

Silicon finally at a level I'm comfortable with. Interesting the reduction in Calcium with increased Magnesium on their detergent package. TBN reserve is better.

I'm staying with this oil.
 

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Suburu Forester, 2014 2.5 n/a. 108000kms on odometer. Time since last oik change 11 months and kms since last oil change 14000kms.

We just purchased the car second hand and the car has afull service history.

Car had Suburu 0w/20 oil also.
Here is the oil analysis
 

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18' 2.5 Premium 6MT
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18' Premium MT, @ 16.6K miles, 6k on oil, 5w30 Idemitsu Eco-Medalist, 1.2 quarts added between changes. Driving a mix of 5-10 miles local and several 50-100+ miles at highway speed, all during hot humid mid-atlantic weather. High Molybdenum likely from moly additives in this oil, low viscosity may be due to top off with 0w-30.
 

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2019 Crosstrek 2018 XT
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14,712 Posts
Interesting to see the mo was so high. That is a good reason for not changing the first oil too soon. Report looks fine to me. But generally kind of a waste of time doing it till say 15K miles.
Thanks for posting.
 
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