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what is the reason mds will not operate with anything other than 5-20 wt. how does a 5-30 negate the mds? tks all

where did you get this info from??? Yes 5-20 is recommended from factory but where does it say that it wont work with other viscosity? I dont see how it would be able to tell the diff between 5-20 and 5-30
 

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I thought the connection with 5W-20 and MDS operation was confirmed by Dodge, and I thought I first read about it in an Allpar article online...but I don't know exactly where that article is now.
 

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Some time back had the dealer change the oil after about 1000 mls the oil change oil change light came on wonder what was going on checked the invoice and the mechanic had put 5w- 30 went back to the dealer changed no problem. I think but who knows that the MDS was working on the 5w-30??
 

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Here is the article
http://www.allpar.com/mopar/new-mopar-hemi.html

Down towards the bottom of the page.

Or TSB 09-015-04 and 09-013-04


Don
That's the article...thanks for finding that Dak. I noticed that they say it "may" cause a conflict with the MDS. Now, the interesting question is "how". The MDS works through the valvetrain lifters from everything I've seen and read...Allpar has one or more excellent articles on this. Hydraulic lifters obviously work on oil as the hydraulic medium. On the MDS models, there's another element functioning to disable the alleged unnecessary cylinders at the appropriate time. So the question would be, does going to a heavier oil possibly disable MDS or does it cause it to malfunction to a point where it comes in at a very inappropriate time? I would lean more toward speculating that MDS wouldn't kick in as frequently with heavier oil, perhaps because the oil is too thick to let the lifters disable those cylinders. But hey...I'm an old GM guy who knows very little about these Mopar engines and all their new fangled, space age technology...LOL!
 

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Discussion Starter · #9 ·
wvcoolvanilla, if your question is for me, i am asking because i was buying some 5-20 oil and was told that since warm weather was coming up i should use a heavier oil. went through the speal about mds and was told that a 5-30 would not affect mds at all. i bought 5-20 anyway.
 

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reason being is that 5/30 gums up the oil galleries over a period of time.
i had one customer with a misfire caused by low pressure for the mds lifters, he was using 5/30. also if you go like 10,000kms between oil changes then you gum up aswell.

the oil passages on the hemi are sensitive to debris. even the screens on the vvt hemi are sensitive, wrong oil can effect the vvt operation aswell.
 

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wvcoolvanilla, if your question is for me, i am asking because i was buying some 5-20 oil and was told that since warm weather was coming up i should use a heavier oil. went through the speal about mds and was told that a 5-30 would not affect mds at all. i bought 5-20 anyway.

Warmer weather in NJ won't be warm enough to need heavier oil. If I don't need it GA you defintiely don't need it in NJ.
 

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Discussion Starter · #14 ·
Warmer weather in NJ won't be warm enough to need heavier oil. If I don't need it GA you defintiely don't need it in NJ.
no i am staying with 5-20 wt oil. i have visited parents in tavares florida for a couple weeks at a time in aug only to find out that it was hotter in jersey than down south, and it was dam hot in florida, we have 100 degree weather here on occasion.
 

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I know from personal experience that it causes the MDS to function erratically and "harshly"...so much so that the dealership went out of their way to make up for their mistake when I went back.
I have noticed that happening on mine since the last time we got the oil changed at the dealership. I'm guessing they put the wrong grade oil in it. That was the last time they are changing the oil anyways.

This is probably a dumb question, but in all my other vehicles I run synthetics. Will a synthetic oil effect the MDS at all?
 

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0W-20 & 5W-20 will work fine with our HEMI engines w/ MDS

I once had a check engine light come on & as i was about to have a job driving quite a distance & back, i called the dealership & went right in
They hooked up the StarScan or what ever it was & it read out something like
IRRATIONAL DATA DUE to ....
I was told at my next service that they had changed the oil & everything went back to normal
They were the only ones that had ever opened my hood, i had not cared enough to look under there at that time. Besides me, they were the only people driving it
-------------------------------------------------------------------------------------

The trick to MDS is this electronically operated valve that allows oil pressure to pump up the exhaust lifter, allowing cylinder pressure to bleed off when the cylinder is not being used. The computer deactivates the cylinder's coil pack and injector during MDS operation, which results in a twenty-percent increase in fuel economy. The entire process happens in milliseconds and is seamless.

http://www.moparmusclemagazine.com/...w_dodge_hemi_engine_information/photo_09.html


Read more: http://www.moparmusclemagazine.com/...ngine_information/photo_09.html#ixzz1tB1Qv0Kg
 

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I like that part "The entire process happens in milliseconds and is seamless."

For something that is 'seamless', I sure do notice it as the truck has a signficant loss of power when the MDS kicks in. Even more noticeable if the MDS kicks in just as you start up a hill.

Darin
 
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