I drank the Delvac 50 KoolAid and I LIKE it!!!

[seafish]

With Fall chores around the ranch mostly done, yesterday I drove the truck into my shop for a few days to catch up on some lightly overdue maintenance. Started by lubing the front and rear diffs, the transfer case and also the G56.

First I replaced the oem Diff covers with Mag Hytechs that I bought used from other guys on some of the forums. I DO recommend using LocTite on the nice allen bolts that MH supplies. Then of course I added the fluid using the DC specd 75w-90 GL5 synthetic gear oil with NO friction modifiers added. The old diff fluid coming out was looking good and there was zero metal finings on the mini magnet drain plugs that I drilled and tapped into the oem diff housing when I changed the fluids the first time at 30k. With the new Mag Hytech covers, I wont be needing those 1/4" Harley Davidson primary case lube plugs anymore, but since I installed them at a low point in the housing, I simply put a new o-ring on them and tightened them back into the housing.NOTE: For those of you wanting a cheap and easy way to drain the diffs WITHOUT having to crack the cover first or having to spend the $$ on MagHytech, I DO recommend them as a cheap, easy and useful mod to the oem diff housing. Drill and tap a 1/4" hole next time you pull he covers for a diff lube job, then thread the plug in, and you no longer have to crack the diff cover to replace the fluid. Easy, peasy, but that being said, those aluminum Mag Hytech covers SURE do look nice underneath the truck and their drain plug and dipstick and thermocouple bung are extremely useful!!!

Transfer case lube was next and upon draining ALSO looked clean with no metal. Despite VERY much wanting to change the fluid to something OTHER then the oem ATF+4, was unable to come up with a replacement fluid that I KNEW would work well, and since New Venture ALSO specd the ATF+4 and it is their TC, I went with it again. Good to go for another 30k!!!

Lastly drained the G56. I had installed an SBC ConOFE single disk clutch/single mass flywheel at 75k (after winning it in a TDR giveaway (hint to TDR Admin that we haven't seen a member prize giveaway in long time!!!) but kept the lube as ATF+4 due to my extended Mopar warranty. Since that ended at 100k, I went ahead and purchased the Mobil Delvac 50 fluid that is the direct replacement for the oem fluid that Daimler specd for the G56 transmission but Chrsyler changed to ATF+4 when they adopted the transmission into the truck. More then anecdotal evidence proves that the ATF+4 fluid is NOT up to the task of keeping the G56 lubed and cooled under heavy loads and while some people are mixing fluids with good results and some others are using Amsoil MTF also with good results, I decided to use the MB spec fluid and I am extremely happy that I did. Eight quarts of Delvac 50 when in through the transmission tower (6 quarts spec, 1 additional for the TransCoolers I added to the case when I did the clutch, and then 1 more quart to keep the front bearing better lubed and cooled )

On test driving today, the G56 upshifts and downshifts MUCH more smoothly and more easily then before and it is also running more quietly!!! IMHO, that is a WIN/WIN/WIN situation. Thumbs up for the Delvac 50, at least in temperate climates like California!!!

Tomorrow, FINALLY a full coolant flush, a complete set of new Mr Bobs silicone hoses and also the addition of a Fleetguard coolant filter on a bracket behind the passenger side front bumper, all per TDR member extraordinaire AH64ID instructions and write ups.

 

[Killer223]

the t-case was designed to use ATF. so your good there.
what brand of oil in the difs?
i switched to amsoil GL-4 in my G56 love it so far.
what brand of antifreeze?

 

[Regcabguy]

The Delvac fluid would definitely quiet the trans down.
Mine was unnerving with ATF+ after chucking the dmf clutch.

 

[seafish]

the t-case was designed to use ATF. so your good there.
what brand of oil in the difs?
i switched to amsoil GL-4 in my G56 love it so far.
what brand of antifreeze?

Like I mentioned, I realize that NewVenture designed and spec'd the NV271 transfer case to use ATF+4 as lube, but I was hoping to find ONE fluid to use in both the G56 and TC. In fact, the Delvac 50 is rated GL4/MT1, and likely COULD be used in the TC as well as the G56, though it might well be a little thick for the TC pump, so I decided NOT to go there just yet without more research from Mobil tech. If it were rated GL5/MT1, like some other lubes, it MIGHT actually be OK to use in the G56, TC and also the AAM diif/sxles, but it is only a GL4 so no go in the axles. Mobil specs say OK to use in GL4 hypoid gears, as well as MT1 trannys, but NOT suitable for GL5 spec hypoid gears,

read more here on Delvac 50 specs and applications--

http://www.mobil.com/english-US/Com...XMobil-Delvac-Synthetic-Transmission-Fluid-50

The Oreillys "house brand" MasterPro GL5 75w-90 synthetic was the ONLY spec'd lube without LS friction modifiers that I could find on short notice to use in the diffs/axles

Xerex G05 HOAT and distelled water are going in after the coolant flush.

 

[seafish]

The Delvac fluid would definitely quiet the trans down.
Mine was unnerving with ATF+ after chucking the dmf clutch.

Dave I am curious if that Amsoil MTF 75/90 that you are running in your truck is API-GL5 rated as well as API-MT1 ??

If, in fact, it is GL5/MT1 rated, then it WOULD be good to use in diffs as well as G56 and possibly even in the TC.

 

[seafish]

In fact, the ORIGINAL MB spec for the G56, Mobil SHC_DC, is a GL4/GL5/MT1 rated 75w/90 gear lube and would likely be FINE to use in both the diffs and G56. Unfotuantely it is no longer manufactured and the Delvac 50, which is only GL4/MT1 is the only available replacment, and is NOT suitable for use in the diffs, only the G56.

http://www.mobil.com/english-GB/Commercial-Vehicle-Lube/pds/GLXXMobilube-1-SHC-75W90

 

[Regcabguy]

The specs are in their literature.I can say that it's the slickest shifting fluid I've used so far.
Easier shifting when cool.

 

[Motorhead]

seafish, I put the Delvac 50 in my G56 about a year ago. The oil has worked well especially in warm weather. Only issue I notice is when the weather turns cold, 40* and below at night, my trans is hard shifting into 3rd for 1 to 2 shifts. I have idled the truck in gear with the transfer case in neutral and it shifts easy first shifts. How is your third gear synchro in your G-56? I got 86k on mine.

 

[Killgore]

Seafish, thanks for the write-up. Next week I will be changing fluid in both the G-56 and differential, installing Trans-Coolers, and drilling and tapping the PML differential cover to install a temperature sensor there as well as in the Trans-Coolers, all of this in preparation for pulling heavy. I have taken delivery of two gallons of the Delvac 50 and five quarts of Valvoline Synthetic 85W-140 and now notice the Valvoline is labeled "LS". Crap! Remembering that Cerb questions the use of the friction modifier in the AAM differential, I called Valvoline and talked with one of their customer service reps concerning the differences between the clutch verses brake functions of the different differentials and was 'absolutely assured' that using their product would be safe. Hope he's right!

I sure hate to dump my Mobil SHC-DC fluid in the transmission, but Delvac 50 is suppose to be the closest thing to it.

- Ed

 

[seafish]

seafish, I put the Delvac 50 in my G56 about a year ago. The oil has worked well especially in warm weather. Only issue I notice is when the weather turns cold, 40* and below at night, my trans is hard shifting into 3rd for 1 to 2 shifts. I have idled the truck in gear with the transfer case in neutral and it shifts easy first shifts. How is your third gear synchro in your G-56? I got 86k on mine.

Motorhead, I only had one day of driving with the Delvac 50 in the G56 before I put the truck back up on blocks for more deferred maintenance-- full coolant flush, add coolant filter, replace all coolant and turbo intercooler hoses with MrBobs Silicone hoses, replace elastomeric harmonic balancer with viscous damper and fan pulley from a 6.7 ISB, as well as replace tensioner, idler pulley and water pump and serpentine belt all with genuine Cummins parts.

All that being said, both upshifting and downshifting with the Delvac 50 was MUCH improved over the notchiness and occasional shift resistance that I WAS getting with the G56 and SMF with ATF+4. As cooler temps are coming now, I will update with more driving. Truck should be back together and ready for a test drice/leak check by the end of the day!!!

 

[seafish]

Seafish, thanks for the write-up. Next week I will be changing fluid in both the G-56 and differential, installing Trans-Coolers, and drilling and tapping the PML differential cover to install a temperature sensor there as well as in the Trans-Coolers, all of this in preparation for pulling heavy. I have taken delivery of two gallons of the Delvac 50 and five quarts of Valvoline Synthetic 85W-140 and now notice the Valvoline is labeled "LS". Crap! Remembering that Cerb questions the use of the friction modifier in the AAM differential, I called Valvoline and talked with one of their customer service reps concerning the differences between the clutch verses brake functions of the different differentials and was 'absolutely assured' that using their product would be safe. Hope he's right!

I sure hate to dump my Mobil SHC-DC fluid in the transmission, but Delvac 50 is suppose to be the closest thing to it.

- Ed

Ed, with the MagHytech covers, I used almost THREE gallons of GL5-75w-90 between the front and rear diffs. The rear diff alone takes 7-8 quarts with the replacement cover. I am curious if your PML diff covers actually increase fluid capacity or not and if you have enough lube on hand to get the job done??

 

[Killgore]

The literature stated an increase of .75 quarts. I couldn't find anything in the instruction manual concerning the stock capacity so I called the dealer and had him check the capacity with my VIN. He came back with 4.25 quarts so I added a total of five quarts. This brought the level in the cover up to just barely below the check hole, fact is, when she's warm the level is right at the check hole.

- Ed

 

[seafish]

The literature stated an increase of .75 quarts. I couldn't find anything in the instruction manual concerning the stock capacity so I called the dealer and had him check the capacity with my VIN. He came back with 4.25 quarts so I added a total of five quarts. This brought the level in the cover up to just barely below the check hole, fact is, when she's warm the level is right at the check hole.

- Ed

Nice...glad you got it done!!!

 

[Wayne M.]

Nice to read a pro-maintenance thread. I just did my fall PM last night. I'm gonna need another set of ball joints.

 

[wildbill]

Can't comment on the Delvac oil, but why a coolant filter?

 

[seafish]

Can't comment on the Delvac oil, but why a coolant filter?

True that the Cummins ISB does not NEED a coolant filter like the Ford 6.0/6.4 or other motors with sand cast blocks, but that being said, I am a filter geek and am hoping that for the minimal extra expense, the cooling system components may have a longer life.

That being said, it was also fun to do and looks REALLY cool right behind the passenger side front bumper valance…LOL!!!
But, in fact, next up is a matching Donaldson hydrualic filter/head on the other side of the bumper, for the PS fluid return lines!!!

 

[GrantP]

But, in fact, next up is a matching Donaldson hydrualic filter/head on the other side of the bumper, for the PS fluid return lines!!!

Please take some pics and share some part numbers! I've been wanting to do the same thing for a while now but haven't figured out all the hardware details and mounting point.

 

[seafish]

Please take some pics and share some part numbers! I've been wanting to do the same thing for a while now but haven't figured out all the hardware details and mounting point.

Will do, though likely not until February or so until I have the downtime to get'rdone.

 

[mwilson]

Sooooo....I don't own a standard and have no horse in the race....

BUT....what do you suppose this fluid is?? It is an Exxon-Mobil product, only available from Daimler Trucks NA. Used in this transmission...

https://www.demanddetroit.com/transmissions/

Now I see "Synthetic Transmission Fluid - Synth 75W-90" and on the back "API GL-4"....Also made in GERMANY.....My local distributors can't even get any info on it..

What do you think it might be under all of that Detroit Diesel packaging????

 

[RVTRKN]

All that being said, both upshifting and downshifting with the Delvac 50 was MUCH improved over the notchiness and occasional shift resistance that I WAS getting with the G56 and SMF with ATF+4. As cooler temps are coming now, I will update with more driving. Truck should be back together and ready for a test drice/leak check by the end of the day!!!

You should monitor the temperature now that your running a heavier oil in your G56. ATF4 is a fluid that has good heat transfer qualities, as well as the Aluminum Case. However my temps with the Mobil Delvac 50 was getting @ 250*+ with just a 15K GCW. I now run a cooler, to maintain no higher than 180*. If you have Geno's trans cool attachments to the PTO's don't expect to see a very big difference, or at least mine didn't anyway. The heavier the oil, the less ability it has to transfer heat.

As far as your transfer case, TDR member "CKelley1" switched to Mobil Delvac 50 for his fleet of CTD's for the TC, or at least the last time we talked he had. You might want to send him a PM, although he'll probably be busy at this time, as New Mexico is getting ready for the winter skiing season.