Mobil Delvac 1 ESP 5W-40 CK-4 - 4,296 Miles - 2010 Subaru Impreza WRX EJ255

a5m

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Aug 9, 2021
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4th UOA. Switched from Castrol Edge 0W-40 A3/B4 used in all previous OCI's.

Almost right after the change went on a 3800 mile round trip to Tucson, AZ, including a 200 mile round trip to Phoenix while there.

Same Mazda RX-8 (N3R1-14-302) Tokyo Roki Filter since acquiring the vehicle with 108,540 miles on Nov 20, 2020.

1333 mi into OCI:
  • Cobb Stage 1 + SF ACN91 v400 Map
Entire OCI:
  • TC-W3 640:1 (Pennzoil Marine Premium Plus) + Red Line SI-1 2.5oz

Significant differences, especially between viscosity. Sampled with motor cold for the first time - let drain for several seconds then filled vials one after another. Can't see that explaining this though.

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Looks good

In 2018 & 2019 I got a deal on many gallons of M Delvac 1 ESP 5w-40, for less than $10/gal. Ran it in my gasoline Toyota w/4.0L for an 11k mile oci, and a couple of times, 6k & 8k mile oci, in my GMC Yukon w/all aluminum 6.2L gasoline engine. Good stuff.
 
Looks good

In 2018 & 2019 I got a deal on many gallons of M Delvac 1 ESP 5w-40, for less than $10/gal. Ran it in my gasoline Toyota w/4.0L for an 11k mile oci, and a couple of times, 6k & 8k mile oci, in my GMC Yukon w/all aluminum 6.2L gasoline engine. Good stuff.
You probably got the better CJ-4 too, not the current CK-4 which this is.

Yea I paid close to that recently with the rebates they had going. If I could've found it closer I would've bought more but the cost of gas didn't make it worth it. Not a lot of farm supply stores near Chicago which tend to sell it in larger quantities.

Agreed this is some stout oil. With the history of Subarus and boxer engines running HDEOs it fits right in. Don't know why BS viscosity tested so much lower, but I'm starting to trust OAI more.
 
Was hoping for a discussion on the variance in tested viscosity. Just spoke with both labs. OAI said they don't see a reason to retest and it dropping to only 13.5 from a starting 13.8 seems normal?? Blackstone said they can retest within a week but I'm sadly outside of that.

In this case I'm more inclined to believe Blackstone. I was hoping to push this OCI but may err on the side of caution and do another ~4500 run and see where it's at. This will be more representative as I mostly do city driving which is tougher on oil than the 90% highway on this one.
 
Another viscosity comparison would be to submit virgin samples from the same bottle to both labs. If one is significantly less that the data sheet, contact the manufacturer. Of course, there could always be batch to batch variation so it can be difficult to pinpoint a precise viscosity or to determine which is the most accurate.

For only $15, I will provide you with a virtual voa with a free TBN. Comments extra. 😜

I wouldn’t worry about it. You can go bonkers trying to figure this stuff out. 🤪
 
Was hoping for a discussion on the variance in tested viscosity. Just spoke with both labs. OAI said they don't see a reason to retest and it dropping to only 13.5 from a starting 13.8 seems normal?? Blackstone said they can retest within a week but I'm sadly outside of that.

In this case I'm more inclined to believe Blackstone. I was hoping to push this OCI but may err on the side of caution and do another ~4500 run and see where it's at. This will be more representative as I mostly do city driving which is tougher on oil than the 90% highway on this one.
I'd be more inclined to believe OAI, as it wouldn't be the first time we've seen Blackstone be off. Phosphorous and Zinc as well as Magnesium are also quite a bit different between the two labs. They were all much closer the last time around.
 
a5m, I think everything looks fine, on either oil. Your prior 3 tests show plenty of variance on a given oil (the Castrol) which shows that those using a UOA & a few PPM difference as “gospel” to be a fool’s errand. People see 1-3 UOAs of an oil in a given engine, and then attribute ALL other variance (even on different engines & drive habits) to “shoddy lab work” while forgetting that the oil manufacturer itself has a tolerance as well. Use the UOA to check viscosity, TBN, and coolant only and you’ll be happy.
 
a5m, I think everything looks fine, on either oil. Your prior 3 tests show plenty of variance on a given oil (the Castrol) which shows that those using a UOA & a few PPM difference as “gospel” to be a fool’s errand. People see 1-3 UOAs of an oil in a given engine, and then attribute ALL other variance (even on different engines & drive habits) to “shoddy lab work” while forgetting that the oil manufacturer itself has a tolerance as well. Use the UOA to check viscosity, TBN, and coolant only and you’ll be happy.
While I'm generally in agreement that UOA PPM variances are wildly over analyzed, we are in this case more looking at the difference in results of the same sample sent to two different labs, so we aren't as much discussing variation from OE spec as much as we are the difference in those results, and why they vary so much, while that didn't seem to be the case on the previous sample.
 
I didn't get notifications for all the replies.

@OVERKILL I agree. Good point about the variation this time being greater than last. Now I'm thinking Blackstone maybe mixed up my sample. The viscosity difference makes no sense, plus everything else. With majority highway miles on a HDEO it's not a stretch the viscosity didn't drop much.

@bluesubie Good idea on the VOA. Get a baseline for each lab. But as you jokingly put it, for my purposes I think that's unnecessary. I'll try and find a sweet spot for OCIs to keep this EJ happy, thinking 5k, and send it.

That Shell Helix looks interesting though... :LOL:
 
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