New Valvoline Synthetic Blend vs 2008 Dodge Ram MDS

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First post here...but I am ditching Conventional Valvoline after 22 years and 650K miles on 3 trucks and need a sanity check. I currently have a 2008 Dodge Ram Half-ton 2WD MegaCab with 2220K miles on the original 5.7 Hemi. Yes, it has a 1-ton drivetrain, giant rear differential, and 8 lug wheels. It is the cross-over year when everything was built as a 1-ton and they just switched the springs and steering gear out before they discontinued the half-ton line of the Mega Cab.

Religiously changed oil at 3K miles and MDS worked perfectly. We can get into the 3K conversation later. There are only two 1-year periods when the MDS did not function correctly. First, when I put Cooper H/Ts on instead of the Michelin tires built for the truck, and the 2nd time is over the last year and a half when I was flip-flopping 5W-20 oils due to availability due to the pandemic.

I removed the like New Coopers after 1 year and put Michelins back on, MDS did not work before the tire shop, and then MDS worked perfectly after new tires were put on. This makes sense because the Coopers weighed about 30 pounds more per tire and had a more aggressive tread making the engine work harder with the same tire size.

When Valvoline Conventional was back on the shelf I switched back from the Valvoline Synthetic, Rotella Truck Synthetic, etc I ran during COVID shortages. Boom.....MDS functions normally except for later when I noticed Valvoline no longer sells a Conventional 5W-20, just a Synthetic Blend that looks like the old Conventional bottles and the MDS stopped working. I called Valvoline customer service and they explained that there is no change in the formula and legally they had to switch all of their "Conventional" labelings to "Synthetic Blend" for legal reasons but it was the same oil.

So I drained out the Valvoline Conventional aka "Synthetic Blend" 5W-20 at 2K and filled it up with the Green Bottle Quaker State Conventional 5W-20 and now the MDS works perfectly as of this week. So I guess whoever sells conventional oils the longest is going to keep the 3rd gen MDS going on the Hemis?

I had to hunt for conventional oil. So Quaker State, Lucas, Tractor Supply Traveller, STP, and some sore brands are holding one strong to conventional oil. It's just weird that I have to run the cheapest oil I can find, sorry Quaker State, to get my MPG back to 16-19 MPG vice the 11-14 MPG it gets with synthetic oil. I am pretty sure next time I am just going to order Lucas or get the $13 for 5 Qts Traveller at Tractor Supply because the others are even getting hard to find.
 
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The MDS system is very finicky in those years. Using 5W-30 often sets a DTC regarding MDS inoperability. Im not sure if Dodge removed that DTC by 2008 or not. Also add the fact that your truck is essentially a 3/4 ton truck and the 5.7 MDS Hemi was never intended for 3/4 usage, I’m not a bit surprised the MDS sometimes doesn’t want to engage. Chrysler was VERY specific about using only 5W-20 in these engines.

Have you tried using a difference brand? Have you tried change oil filter brands?
 

Marty165

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The MDS system is very finicky in those years. Using 5W-30 often sets a DTC regarding MDS inoperability. Im not sure if Dodge removed that DTC by 2008 or not. Also add the fact that your truck is essentially a 3/4 ton truck and the 5.7 MDS Hemi was never intended for 3/4 usage, I’m not a bit surprised the MDS sometimes doesn’t want to engage. Chrysler was VERY specific about using only 5W-20 in these engines.

Have you tried using a difference brand? Have you tried change oil filter brands?
It was like clockwork during the pandemic when I was switching back and forth between synthetics and conventional based on availability. As soon as synthetic or synthetic blend went in the MDS shuts off. There has to be a Dodge guy somewhere that knows the system better than me and some rough math on weight conversions with synthetics to keep the MDS on.

The only 2 filters that have ever been on it are the Frams and Purolators.
 
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Paging @NHHEMI

Found one of his posts from '09.
mdsCapture.JPG
 

OVERKILL

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This doesn't sound right at all. The MDS system is pretty simple, but it does use load and throttle angle to dictate whether it comes on and to kick it off. I think you have something else going on, the system simply isn't this sensitive to viscosity; it can't be, otherwise it would never engage in the winter, as temperature has a far greater impact on viscosity than the grade on the bottle.

We owned an '06 Charger R/T with MDS and the system worked flawlessly, but this is a pretty heavy truck for 4-popper mode, so if something's a bit "off" it could prevent it from engaging.

Later years the system became far more aggressive. Our DT will go into MDS as soon as it can, which means it is in and out of it a lot in town and it takes some noticeable manipulation of the throttle to get it to kick off. My SRT's have all been significantly less aggressive, you have to be very steady-state for it to kick on and it will kick off at the slightest hint of throttle.
 
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That's very odd.

Did the oils that didn't let the mds function well have the chrysler ms spec on the back as that's supposed to be the mds spec.

Also make a list of all the oils that worked well for you and simply try to find prices and availability and order them online or for in store pickup from Walmart, tractor supply, Lowes, home depot, amazon, and any others if you want. Not a lot of work it's pretty quick.

Just make a tab of each website on your computer and on each website search every oil in that's good and check to see if they have any and if it meets their free shipping if minimum x order amount is met or for in store pick up and add them to the cart. Then go to the next website and rinse and repeat and once you're done you can just click between websites on the shopping cart page to see which has the best pricing per jug and if they free shipping or in store pickup so you can easily make your choice.
 
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@Marty165 directly from Chrysler….

I knew something sounded weird when I read your post. As I stated earlier the HEMI MDS was never intended for 3/4 ton usage. If you are down on fuel economy then something else is going on. Good luck
7AF5D9C9-C7DB-4B4F-903E-98CD9DDBD43B.jpeg
 
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OVERKILL

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That's very odd.

Did the oils that didn't let the mds function well have the chrysler ms spec on the back as that's supposed to be the mds spec.

Also make a list of all the oils that worked well for you and simply try to find prices and availability and order them online or for in store pickup from Walmart, tractor supply, Lowes, home depot, amazon, and any others if you want. Not a lot of work it's pretty quick.

Just make a tab of each website on your computer and on each website search every oil in that's good and check to see if they have any and if it meets their free shipping if minimum x order amount is met or for in store pick up and add them to the cart. Then go to the next website and rinse and repeat and once you're done you can just click between websites on the shopping cart page to see which has the best pricing per jug and if they free shipping or in store pickup so you can easily make your choice.
MDS is not that sensitive, it can't be due to ambient temperature's impact on viscosity. The Chrysler spec has nothing to do with MDS operation.
 
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My question is then why he think he has MDS. It would "rumble" on the earlier trucks (and I can feel it in my SRT) but you can't feel it on the DT's, we only know it comes on and off because of the exhaust note (ours has aftermarket exhaust).
Good question, I’m curious about this one as well. Cylinder deactivation doesn’t affect RPM so he couldn’t have been using the tachometer to come to this conclusion. Maybe exhaust note or engine vibration? No idea, but would love to hear the rest of the story. Unless maybe the engine was replaced with a HEMI MDS engine and all the associated ecu controller hardware?
 
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MDS functions normally except for later when … the MDS stopped working.

What indication(s) does the vehicle give you that you can use to tell when MDS is engaged or not?

Also, if the MDS system truly stopped working, there should be one or more corresponding DTCs stored in the PCM that would indicate a problem has occurred and which part of the emissions system the problem might affect.

If there was no CEL or stored codes, the MDS system didn’t quit working so much as it stopped engaging in the scenarios it normally would.

Here again, I am wondering what behavior is missing that you can key off of to know the MDS has remained disengaged when it normally should have been.
 

Marty165

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Dec 7, 2021
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This doesn't sound right at all. The MDS system is pretty simple, but it does use load and throttle angle to dictate whether it comes on and to kick it off. I think you have something else going on, the system simply isn't this sensitive to viscosity; it can't be, otherwise it would never engage in the winter, as temperature has a far greater impact on viscosity than the grade on the bottle.

We owned an '06 Charger R/T with MDS and the system worked flawlessly, but this is a pretty heavy truck for 4-popper mode, so if something's a bit "off" it could prevent it from engaging.

Later years the system became far more aggressive. Our DT will go into MDS as soon as it can, which means it is in and out of it a lot in town and it takes some noticeable manipulation of the throttle to get it to kick off. My SRT's have all been significantly less aggressive, you have to be very steady-state for it to kick on and it will kick off at the slightest hint of throttle.
Hmm, the winter comment is interesting. I will keep an eye on the temps and time of the season if I switch back and let you know.
 

Marty165

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What indication(s) does the vehicle give you that you can use to tell when MDS is engaged or not?

Also, if the MDS system truly stopped working, there should be one or more corresponding DTCs stored in the PCM that would indicate a problem has occurred and which part of the emissions system the problem might affect.

If there was no CEL or stored codes, the MDS system didn’t quit working so much as it stopped engaging in the scenarios it normally would.

Here again, I am wondering what behavior is missing that you can key off of to know the MDS has remained disengaged when it normally should have been.
Indications-The engine bump when it engages and disengages. This along with MPG difference when conventional and synthetic is used.
 
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