Oil sample reports, Blackstone vs Polaris side-by-side...

2000 detroit series 60 12.7
1,492,000 odometer
~750,000 on inframe
~600,000 on 6-pack
15,000 on oil
OPS eco-pur
Mobil delvac conventional
Dipstick drops from full to 9/10 in 15,000 miles
No coolant loss
Hot oil pressure drops from 48psi @ 1250 rpm to 45psi in 15,000 miles
8mpg over last 25,000 miles (actual -- not ecm)


I changed the oil after purchasing this truck & sent a sample of the reportedly 20,000-mile old oil to blackstone. Over a month later (apparently, USPS does not like it when you send it in the plastic shipping jar -- box it instead), the results came back with alarmingly high lead.

So at the next oil change, I took 2 samples back-to-back and sent one to Blackstone & one to Polaris (this time boxing the jars). The samples were taken from the OPS's sample port as the engine was idling down after 8 hours on the highway. The original sample was taken mid stream during a cold oil change.

Blackstone (sample analyzed in 4 days) said this sample was good and suggested increasing the change interval to 18,000. Polaris (sample anaylzed in 5 days) flagged fuel dilution & showed a little more lead than the same oil at blackstone.

Given the unreasonable lack of oil consumption and the high lead on the first sample, I'm inclined to trust Polaris a bit more (incidentally, Polaris's tests cost a bit less).


Thoughts? I don't idle, which Polaris said could cause fuel dilution, but I do cruise at 1250 rpm which is kinda low for a 12.7... Should I do any additional diagnosis or just throw in a new 6 pack? I've been wanting to retrofit an engine brake anyway (delayed my plans after getting 1st oil report back)

 

2001 International 9400 with the 12.7 pulling a ribbed 1998 Monon dry van OTR at 55mph. Meritor 10spd direct, 2.64 rears, twin screw, lugged dual tires (aired to 130psi), cab extenders but no other aerodynamic skirting, loads weighing from 10 to 48k, & a decent driver.

I'll try to call in today, but the timing isn't great - I may be busy trying to book my next load...

Would that advice be the same if you were going to be doing significant engine work in the meantime (bullgear, jake retrofit & overhead, maybe a new damper, etc)?

 

Unfortunately, I haven't had ANY luck with local shops -- including the 2 detroit-authorized service centers. Besides, I'm OTR 330 days/year -- its easier to mail it & deal with the same person all the time.

Speaking of that, I emailed both Blackstone & Polaris their competitor's reports. Blackstone responded almost right away:

 

KR said not to worry, Polaris' 3.6% fuel dilution is really more like 1.6%