Synthetic or Comventional?

[Boaring1961]

I have around 320k miles on three different cummins since 2005 and have only used Delo 400 15W-40 in every truck. Sold my last 2005 to a buddy and he's at 300K+ now. I've had most, but not all, of my oil sent in for analysis. I personally don't see the need for synthetic, but may change my mind if I lived somewhere cold. Where I live (coastal) if it gets 35 degrees on a December or January morning it's bitterly cold!!

 

[OLEJOE]

My 18’ is still under warranty and requires 6 month changes and has only had 1 change so far. I’m going to use VPB and Delvac 1300 I got on sale along with the Stratapores I got on sale also. This is better stuff than a lot of them with hundreds of thousands miles have been privy to.

 

[AH64ID]

I'll always run a synthetic, to my understanding it is made by replicating only the GOOD properties of a conventional. Plus its only slightly more expensive for the peace of mind IMHO, in that respect its worth every penny.

In the winter-Spring I'll run 5w-40. We won't see much of 0 degree weather but I'll say this oils in the truck till its 50 degrees outside. I notice lower oil pressure at startups (5w oil flows better at cold temps) and I get oil pressure faster which makes me happy.

I mean the 40 part of the oil is really the only concern, in theory its the same viscosity as a 15w-40 at operating temp, right?

No real point in going back and forth between 5w-40 synthetic and 15w-40 synthetic, as the 15w-40 has all the pour point most people need.

Your oil pressure gauge is fake, it tells you nothing worth even looking at.

There are several other properties that make a 15w-40 synthetic slightly better than 5w-40 synthetic, which is why I run 15w-40 synthetic year round.

 

[Cummins12V98]

5-40

 

[kthaxton]

I run 5w-40 year round and it certainly isn't a waste of time. It lubes my engine.

 

[Cummins12V98]

"Waste of time" is changing every season if temps don't dictate doing so.

 

[TFucili]

15W40 is not even on the menu for the new Cummins, so I'm jealous

 

[AH64ID]

15W40 is not even on the menu for the new Cummins, so I'm jealous

But 10w-30 is. Makes me wonder if it’s emissions/economy based or if the redesigned motor really doesn’t need a 40wt.

The low temp recommendation is still 5w-40 thou.

 

[Newsa]

I've used 15w 40 synthetic down to neg 15 or neg 20 Fahrenheit. And have metals less than 15 ppm in oil analysis. Engine makes noise at that temp, but it doesn't show in the UOA's.

Not comfortable using 5w 40 because it's basically 5 weight oil with a bunch of additives! 15w 40 has enough additives. I don't want more additives because the additives don't lubricate.

 

[TFucili]

But 10w-30 is. Makes me wonder if it’s emissions/economy based or if the redesigned motor really doesn’t need a 40wt.

The low temp recommendation is still 5w-40 thou.

My first reaction is chasing fuel economy, but if that's so they didn't chase it very far. Then there's the new-to-them hydraulic roller lifters to consider. I am running T6 5W40, but if a deal comes along on Delvac or Delo or Pabst... errr... Premium Blue, that is fine too. After that fussazz clattering 6.4 Hemi, I'm glad to be back to an engine that doesn't turn its nose up at the wrong pedigree oil.

 

[kthaxton]

I've used 15w 40 synthetic down to neg 15 or neg 20 Fahrenheit. And have metals less than 15 ppm in oil analysis. Engine makes noise at that temp, but it doesn't show in the UOA's.

Not comfortable using 5w 40 because it's basically 5 weight oil with a bunch of additives! 15w 40 has enough additives. I don't want more additives because the additives don't lubricate.

You are using a conventional oil mindset. Synthetics require very few polymers to achieve a wide span such as 5w 40.

Ram and Cummins are comfortable with it, you should be too.

 

[DeansRedRam]

But don't get me wrong. I won't change out that 5w-40 prematurely with the change of season. I will always wait til it is up on mileage.

I should have stated I'm talking in regards to my 2001 24v. Sorry about that, I get so caught up in my own head I don't explain well.

I have a video on my phone (of course I can't find it now) where it was one morning start up with 5w-40 vs 15w-40 and I had oil pressure earlier on the 5w-40. It was about 15 degrees out both mornings.

The stock oil pressure gauge in that truck seems very accurate to me responding to changes in temps.

 

[Newsa]

You are using a conventional oil mindset. Synthetics require very few polymers to achieve a wide span such as 5w 40.

Ram and Cummins are comfortable with it, you should be too.

Easy to have a conventional oil mindset when the majority of 5w 40 synthetics (type III) are really just highly refined conventional oil that means the molecule size is more consistent and uniform, but they are not really engineered like the higher quality Type IV and Type V synthetics that do have the intrinsic ability to thicken when warmer/hotter. There are a few 5w 40 type IV and V, but the majority of 5w 40's are really just highly refined conventional/mineral oil.

I am just stating my preference. Feel free to make your own decision about your truck.

 

[Newsa]

You are using a conventional oil mindset. Synthetics require very few polymers to achieve a wide span such as 5w 40.

Ram and Cummins are comfortable with it, you should be too.

Easy to have a conventional oil mindset when the majority of 5w 40 synthetics (type III) are really just highly refined conventional oil that means the molecule size is more consistent and uniform, but they are not really engineered like the higher quality Type IV and Type V synthetics that do have the intrinsic ability to thicken when warmer/hotter. There are a few 5w 40 type IV and V, but the majority of 5w 40's are really just highly refined conventional/mineral oil.

Edit: and that type III 5 weight oil is more uniform so it should even be thinner than conventional 5 W.

I am just stating my preference. Feel free to make your own decision about your truck.

 

[Newsa]

double post

 

[Newsa]

Triple post. Internet got a bug

 

[lpennock]

Triple post. Internet got a bug

Better self quarantine for 14 days since you have now been exposed.

 

[Newsa]

J

Better self quarantine for 14 days since you have now been exposed.

Just a case of kennel cough

 

[MtnRider]

I've been running Valvoline premium blue 15w-40 conventional from day one in my 2016 with no issues. I live in Georgia so no need for the 5w-40.

I see a few people saying they run full synthetic 15w-40, what brand are you using? The only ones I can find in that weight are "blends" unless I look at some of the "guccci" high $ oils (amsoil etc)? Is there full synthetic 15W-40 in a more common brand?


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[dieselshadow]

Shell Rotella T6.