M939 Oil Change, Best Oil, Tips and Tricks

[Steelreaper80]

What oil change intervals are people running with the 8.3? My truck is used as a tow vehicle pulling about 18K out of state multiple times a month. I changed mine at 7K? Too long, too short?

I downloaded the Cummins engine manual. I use mine A LOT. It is now basically a regional haul truck pulling my tractor everywhere for mowing. The manual states 10,000 miles or 500 hours. If you are not using your truck that much it has a graph to show you when to change it. I would attach it but the file is too big for the site......

 

[charlesmann]

@simp5782
can you message me the info/link to your bypass filter? my oil psi seems normal, but again, the gauge can be faulty, as with my eng temp (dang thing will peg out either direction if i slightly rotate the gauge in the dash). as for an oap (oil analysis program, who do you recommend? i can't for the life of me, remember who we were using to test our acft oils and hyd, but i do remember they were in spokane, wa. but from what i was told, those people were not cheap ($75 per sample) and we have 2 engines, 3 xsmns and 3 hyd systems. that adds up quick. i was thinking of adding a lubrifiner (what i think you calling a bypass filter kit) and doing samples on my cummins p/u truck, even though its 2 yrs old and only has 16,000 miles on it.

 

[simp5782]

@simp5782
can you message me the info/link to your bypass filter? my oil psi seems normal, but again, the gauge can be faulty, as with my eng temp (dang thing will peg out either direction if i slightly rotate the gauge in the dash). as for an oap (oil analysis program, who do you recommend? i can't for the life of me, remember who we were using to test our acft oils and hyd, but i do remember they were in spokane, wa. but from what i was told, those people were not cheap ($75 per sample) and we have 2 engines, 3 xsmns and 3 hyd systems. that adds up quick. i was thinking of adding a lubrifiner (what i think you calling a bypass filter kit) and doing samples on my cummins p/u truck, even though its 2 yrs old and only has 16,000 miles on it.

Blackstone labs in Ft Wayne Indiana is like $20. They will send you a kit.

Oil Analysis | Blackstone Laboratories

Learn what's going on in your engine with oil analysis. Our free kits are easy to use and we explain the results in plain English! Since 1985.

www.blackstone-labs.com

I used a puradyn pft24 system.

Member @Suprman has them for sale. Or found on ebay. Puradyn says 65000mi or so from an oil change.

Fleetguard oil filter LF734 is 95% efficient for the spin on.

 

[charlesmann]

@simp5782
thank you sir for the lab and the attachment. and yep, what my dad used to refer to as a lubrefiner is what you call a bypass. his old truck had a centrifuge filter that then drained and got sent to a, well, I'm assuming, around 1-3 micron filter, or whatever micron there was back 25 yrs ago.
again, that you for the insite.

 

[simp5782]

@simp5782
thank you sir for the lab and the attachment. and yep, what my dad used to refer to as a lubrefiner is what you call a bypass. his old truck had a centrifuge filter that then drained and got sent to a, well, I'm assuming, around 1-3 micron filter, or whatever micron there was back 25 yrs ago.
again, that you for the insite.

The m915 series trucks have the firewall mounted luberfiner. The puradyn is less than 1 micron and adds additives when the oil goes thru it.

 

[jminker]

I run Shell Rotella 15W40 (Heavy Duty not synthetic) in my 923A2. The OE/HDO I believe is Oil Engine/ Heavy Duty Oil, I seam to remember reading it in one of the TM definitions. When you remove the plug from engine pan watch for the washer, mine was very hard to see and got dropped in to drained oil bucket, ya I had to fish it out. As for Wally World I buy my oil where ever it is on sale or lowest price.
Your procedure is sound, on #4 be sure to apply oil to gasket on filter and don't over tighten. #'s 6 and 7 are good, let engine run to circulate oil then shut down and let it settle to get an accurate measurement on dip stick.

Good luck

I recently purchased a 1990 M923A2 with 8.3L 6CTA engine and wanted to know how many gallons of oil it takes to when I include changing the oil filter? In TM-9-2320-272-10 on pg 28 (1-20) it refers to M939/A1 and /A2 and their capacities but not specifically the M923A2 and was just wondering if it was the same?

Thank You!!

 

[98G]

I recently purchased a 1990 M923A2 with 8.3L 6CTA engine and wanted to know how many gallons of oil it takes to when I include changing the oil filter? In TM-9-2320-272-10 on pg 28 (1-20) it refers to M939/A1 and /A2 and their capacities but not specifically the M923A2 and was just wondering if it was the same?

Thank You!!

This information should be on a dataplate on the dash. 5 gallons iirc

 

[jminker]

This information should be on a dataplate on the dash. 5 gallons iirc

Thank you!! The dataplate was removed.

 

[Jbulach]

20 Qts according to my plate

 

[jminker]

View attachment 807839 20 Qts according to my plate

Thanks!!!