5w20 or 5w30

[chrisbh17]

5W-20 is what you should use, year 'round. For all of us to do the same . Way to much brain cells burned on this subject when the real answer sis right in front of most all of us, NO real reasons to do any different than the 5W-20, ever.

Cam and lifter failures are a great reason to speculate.

 

[kurek]

I'm still curious what advantage higher viscosity is supposed to offer. My wife's mustang has been on a steady diet of 5w20 since 2001 is it gonna explode if we don't start pouring molasses in it?

 

[chrisbh17]

The idea is that a thicker oil will "film" over the parts better than a thinner.

Picture taking a sheet of metal and pouring cooking oil on it. Then lift the sheet to a 45 degree angle and watch the oil pour off. It doesnt immediately shed all of the oil, it kinda runs its way down the metal and eventually all of the oil comes off.

Now think of that happening many times a second as your engine parts rotate. A film of oil gets splashed or sprayed onto a lifter, the oil "sheets" down the lifter, cam, etc. Then the process repeats.

A thicker oil will take longer to "sheet" off the moving parts, which provides more protection until more oil can be splashed/sprayed back on.

In the realm of Hemi cams and lifters, the more oil you can get to stick in place, the better. One of the theories behind the cam/lifter failure is a lack of oil towards the rear of the engine, especially at low RPMs. A 5W-30 oil will "stick" longer than a 5W-20. HTHS rating is a good measurement for how long an oil will protect before it sheets off and disappears.

 

[FaceDeAce]

It is not a matter of “advantage”.
The matter is what viscosity the design basis was for the engine oil pump, oil galleries, tensioners, lifters, journal clearances, seals and gaskets.

A range of viscosity indices will work. Wrt 5w20 vs 5w30 the difference is so little, ... it makes little difference. Use either. Use whatever blows your hair back and keeps the wallet fat.

 

[chrisbh17]

It is not a matter of “advantage”. The matter is what viscosity the design basis was for the engine oil pump, oil galleries, tensioners, lifters, journal clearances, seals and gaskets.

Keep in mind, up until the 2017 model year, the owners manual stated you could use 5W-30 if necessary.

Starting in 2017 that note was removed. But NOTHING about the engine changed, so the oil pump, galleries, lifters, clearances were clearly able to handle 5W-30 without issue.

 

[Wild one]

Keep in mind, up until the 2017 model year, the owners manual stated you could use 5W-30 if necessary.

Starting in 2017 that note was removed. But NOTHING about the engine changed, so the oil pump, galleries, lifters, clearances were clearly able to handle 5W-30 without issue.

The non-mds 5.7 manual tranny Challengers call for 5W-30,same basic engine except no MDS,the earlier non-mds 5.7's in the HD's also call for 5W-30.

 

[chrisbh17]

The non-mds 5.7 manual tranny Challengers call for 5W-30,same basic engine except no MDS,the earlier non-mds 5.7's in the HD's also call for 5W-30.

Yep. I think that causes some of the "5W-20 is for MDS to work" misconception.

There are people running 40 weight oil in an MDS engine and MDS still operates just fine.

 

[Gero]

5W-20 is what you should use, year 'round. For all of us to do the same . Way to much brain cells burned on this subject when the real answer sis right in front of most all of us, NO real reasons to do any different than the 5W-20, ever.

I thought good quality synthetic 5w20 (pup) would be fine but when the motor developed a ticking noise after 5 or 6000miles, I knew there was something wrong. The ticking noise is significantly quieter with pup5w30.

 

[Wild one]

Yep. I think that causes some of the "5W-20 is for MDS to work" misconception.

There are people running 40 weight oil in an MDS engine and MDS still operates just fine.

I run 5W-30 in my wifes stock 2016 5.7 Challenger,the mds still kicks in,is it noticeable "yes" but only if you're paying attention for it.I've never told her i'd switched her car over to 5W-30,just to see if she'd notice the change in the mds's operation,and she never has,so it's not as noticeable as a lot of guys think,lol

 

[pacofortacos]

I'm still curious what advantage higher viscosity is supposed to offer. My wife's mustang has been on a steady diet of 5w20 since 2001 is it gonna explode if we don't start pouring molasses in it?

You might want to switch over if she starts towing 4-7000 lbs behind her @ highways speeds in 90 deg heat - just saying.

 

[Burla]

The entire reason for this being an issue with Rams is because of the cam/lifter issues. If not for this, it would be less of an argument between what weight oil to run, or what additives you want in your oil. Most applications lubrication choice doesn't really matter, cheapest synthetic is the way to go.

 

[Pines19]

Ok, I’m not the best mechanical, but is the cam lifter issue for sure oil related or maybe mds related? I thought about going to 5w30,but started shutting off mds and tick went away almost immediately. Runs smooth.

 

[Burla]

Most aren't mds related, and the issue is with non mds 6.4 hemis as well. Sounds like you got lucky.

 

[Rampower2012]

I use full synthetic mobile 5 W 20 I would go whith full synthetic better

 

[kurek]

You might want to switch over if she starts towing 4-7000 lbs behind her @ highways speeds in 90 deg heat - just saying.

We live in Phoenix and she treats the gas pedal like an on/off switch 100% of the time. Maybe film strength isn't a product of viscosity and lower viscosity flows more volume.

 

[Burla]

We live in Phoenix and she treats the gas pedal like an on/off switch 100% of the time. Maybe film strength isn't a product of viscosity and lower viscosity flows more volume.

Does it flow more volume when warm? How much more?

 

[kurek]

Does it not? Are you seriously trying out burden of proof right now for following the directions?

 

[pacofortacos]

We live in Phoenix and she treats the gas pedal like an on/off switch 100% of the time. Maybe film strength isn't a product of viscosity and lower viscosity flows more volume.

Then again maybe film strength is a product of viscosity.

Let's ask this question. For trucks that operate under a certain load one weight oil is rec. BUT when operating with a heavier load another oil is specified - same engine, same truck.

NOTE: For 2500/3500 trucks with a 5.7L engine operating
under a gross combined weight rating of 14,000 lbs
(6 350 kg) or greater, SAE 5W-30 meeting FCA Material
Standard MS-6395 engine oil is recommended for all
operating temperatures.

It sure does seem as if the engineers do not think the light oil is up to heavy duty tasks. That is basically a 2500 truck with a 7000# load.
NOTE 2500 and up trucks don't need to meet CAFE requirements.


I seriously doubt that in a fixed pump with fixed orifices that there is a significant volume difference between oils of with such a small viscosity difference.

It takes a bit more power to pump a thicker viscosity but a oil pump such as used in motors is going to output a certain volume per revolution - unless the pressure relief is dumping the oil.

 

[kurek]

I seriously doubt that in a fixed pump with fixed orifices that there is a significant volume difference between oils of with such a small viscosity difference.
It takes a bit more power to pump a thicker viscosity.

Fixed orifices is the actual way oil viscosity is measured.. And it's either too small a difference to matter or it's not. If it's too small a difference to matter then going off script is just **** to be contrarian, or if it does matter then it matters equally for all considerations even the ones that don't support the theory being promoted.

 

[pacofortacos]

So what is your theory for rec. a heavier oil on a loaded 2500?

I would be willing to bet on a heavier oil needed for crankshaft protection. There is a bit less leakage with a heavier oil.