2024 Subaru WRX; Mobil 1 mixture 0w-20 0w-30, 2k mi

[thelazyhero]

1QT Mobil1 Racing 0W-30 + 4QT Mobil1 EP 0W-20

Had a bunch of 0W-20 lying around and a couple Mobil1 Racing 0W-30. I wouldn't run the Mobil1 Racing by itself but felt iffy about running 0W-20 on this motor to begin with since I tend to push the vehicle pretty hard.

This would have been my 2nd oil change. 1st being at 995 miles which I unfortunately didn't get an analysis but figured I can grab this oil change. I think the extra silicon could also be that I didn't handle it entirely properly as I dropped it a couple times, etc, but yeah. I'll do a better care next time on the bottle itself. That said, the Mobil1 Racing seemed to have beefed up the 0W-20 somewhat.

What does everyone else think? The copper wear kind of upset me but I figure it's normal for initial break-in. I'll be changing out the oil at 3000 miles to hopefully see the level drop down a bit.

 

[Lubener]

I always thought an analysis is a waste of time on an engine which isn't fully broken in. There is always going to be wear metals present.

 

[twX]

Silicon and copper are always very high on these engines during break in. The silicon is from engine sealant and the copper is from the oil cooler. Both are harmless.

The 12 ppm tin would be concerning if not for the fact that SpeedDiagnostix reports very often have erroneous high tin measurements. I'd switch to a different lab for your next UOA. I believe the rod bearing overlays are tin-based on these engines, so it's a metal you'll want an accurate measurement of.

 

[Rand]

how is the fuel dilution tested for at that lab?
seems under reported.
2000miles and its 7.1 with a quart of 0w30?
I'd guess its likely 3% or higher.

Silicon and copper are normal for new engine.

The FA24DIT is a fuel diluting oil thinning engine.
Not a believer of 0w20 in it myself.
at a min I'd go standard 0w30 or 5w30.. if not a thicker euro 0w30 or 5w30

I'd wait on UOA until you have 10000 miles on engine.. pretty worthless before that.

5000mile oci max IMO.

 

[thelazyhero]

Silicon and copper are always very high on these engines during break in. The silicon is from engine sealant and the copper is from the oil cooler. Both are harmless.

The 12 ppm tin would be concerning if not for the fact that SpeedDiagnostix reports very often have erroneous high tin measurements. I'd switch to a different lab for your next UOA. I believe the rod bearing overlays are tin-based on these engines, so it's a metal you'll want an accurate measurement of.

Who would you recommend to perform the UOA?

 

[twX]

Who would you recommend to perform the UOA?

Blackstone or Oil Analyzers (OAI). OAI is better if you want fuel dilution to be accurate.

 

[thelazyhero]

how is the fuel dilution tested for at that lab?
seems under reported.
2000miles and its 7.1 with a quart of 0w30?
I'd guess its likely 3% or higher.

Silicon and copper are normal for new engine.

The FA24DIT is a fuel diluting oil thinning engine.
Not a believer of 0w20 in it myself.
at a min I'd go standard 0w30 or 5w30.. if not a thicker euro 0w30 or 5w30

I'd wait on UOA until you have 10000 miles on engine.. pretty worthless before that.

5000mile oci max IMO.

What are you running in your Outback? We practically have the same engine.

Blackstone or Oil Analyzers (OAI). OAI is better if you want fuel dilution to be accurate.

Blackstone has their own issues which is why I tried SpeedDiag. Maybe I'll look into Oil Analyzers.

 

[Rand]

Who would you recommend to perform the UOA?

OAI so you have accurate fuel dilution number. they use actual test with GC instead of inferred from flashpoint(blackstone)

What are you running in your Outback? We practically have the same engine.

I am currently running m1 ESP 0w30. I will likely be using that or m1 esp 5w30 both of which are already sitting on shelf in basement.

I had 3k mile UOA from winter that showed 5%+ fuel dilution on a run of m1 EP 5w30.
If I had run 0w20(and a normal 5k mile oci) it would have been severely thin/out of grade.

Thread 'M1 EP 5w30 3.2k mi; Subaru Outback XT 2.4L FA24DIT'

Apr 20, 2025

Just got this back.. fairly interesting but expected.
oil was in use from 12-17-24 to 4-12-25 (4 months)
mileage from 11111 to 14273 (3161mi)
Sump capacity 5qt.

• Rand
• Replies: 41
• Forum: Used Oil Analysis - Gasoline

• 

 

[thelazyhero]

OAI so you have accurate fuel dilution number. they use actual test with GC instead of inferred from flashpoint(blackstone)

I am currently running m1 ESP 0w30. I will likely be using that or m1 esp 5w30 both of which are already sitting on shelf in basement.

I had 3k mile UOA from winter that showed 5%+ fuel dilution on a run of m1 EP 5w30.
If I had run 0w20(and a normal 5k mile oci) it would have been severely thin/out of grade.

Thread 'M1 EP 5w30 3.2k mi; Subaru Outback XT 2.4L FA24DIT'

Apr 20, 2025

Just got this back.. fairly interesting but expected.
oil was in use from 12-17-24 to 4-12-25 (4 months)
mileage from 11111 to 14273 (3161mi)
Sump capacity 5qt.

• Rand
• Replies: 41
• Forum: Used Oil Analysis - Gasoline

• 

What's your use case like? 5% is quite a bit indeed. I assume all my spirited driving and track days will only make the fuel dilution worse not better?

 

[berniedd]

Not too much to learn from a UOA at 2000 miles from new. The break in wear stuff is still leaching into the oil and will naturally be elevated beyond "normal" levels. I'd wait till the engine is fully broken in. That may take beyond 10,000 miles.

 

[bluesubie]

Presume the racing oil was a one time thing since you had it lying around? I wouldn’t run a high SAPS racing oil in a Subaru DIT. Subaru Japan no longer recommends the high SAPS Subaru branded Castrol 5W-40 that they used to.

I see comments even from tuners that 93 octane leads to deposits, but I suspect there are a lot of people running high SAPS oils out there. I know there is someone on the Outback forum that installed an AccessPort and immediately went for the Brotella 5W-40.

IAG Performance began recommending reduced SAPS Euro oils early in the days of the FA20DIT.

 

[thelazyhero]

Presume the racing oil was a one time thing since you had it lying around? I wouldn’t run a high SAPS racing oil in a Subaru DIT. Subaru Japan no longer recommends the high SAPS Subaru branded Castrol 5W-40 that they used to.

I see comments even from tuners that 93 octane leads to deposits, but I suspect there are a lot of people running high SAPS oils out there. I know there is someone on the Outback forum that installed an AccessPort and immediately went for the Brotella 5W-40.

IAG Performance began recommending reduced SAPS Euro oils early in the days of the FA20DIT.

Yup. I just had a bunch of 0W-20 lying around and a couple quarts of 0W-30 Racing. My use case would not warrant 0W-20 and wanted a bit of protection during break-in that the Racing oil would provide. I also have a 0W-50 Racing that I thought about using again for these super short OCIs.

Honestly, if I could just sell the oil, I would. Especially the 0W-20 EP since I have like 11 quarts left still. I "might" consider using the 0W-20 in the winter time but **** me I have no discipline about staying civil and I know I'll still be spinning the car around in the snow.

 

[thelazyhero]

Not too much to learn from a UOA at 2000 miles from new. The break in wear stuff is still leaching into the oil and will naturally be elevated beyond "normal" levels. I'd wait till the engine is fully broken in. That may take beyond 10,000 miles.

I know. It's just one of those goofy "this guy is weird" kind of thing where I bought the car brand new where I picked up with only 7 miles on the odometer and I want the paperwork on oil changes and maintenance including the OCI. I don't usually buy new cars so it's just that.

 

[SubieRubyRoo]

Blackstone or Oil Analyzers (OAI). OAI is better if you want fuel dilution to be accurate.

OP would be better off burning his $38 and asking a carnie during the county fair what his oil sample looked like than your first option.

They’re so bad these days that the only reason they’re called a laboratory is because it’s the business’s proper name, NOT because you can trust their people wearing white coats. The whole point of paying someone to analyze something implies you expect some semblance of reality and veracity when you review the results.

 

[thelazyhero]

OP would be better off burning his $38 and asking a carnie during the county fair what his oil sample looked like than your first option.

They’re so bad these days that the only reason they’re called a laboratory is because it’s the business’s proper name, NOT because you can trust their people wearing white coats. The whole point of paying someone to analyze something implies you expect some semblance of reality and veracity when you review the results.

Word. Once I read Blackstone, my critic glasses slipped on by itself for everything else that was said.