15w-40 vs. Straight 30??

[Justin]

Well, I'm back...

I keep finding myself back at this site everyday although I said I had swore it off after my little fiasco with Patman.

Anyways, as you know, I'm running Delo 400 15w-40 in a '95 Chevy Lumina (3.1L V-6). It has seen a pretty hard life (relativitely speaking.) Heck, last weekend, it pulled around a 14ft. trailer (with a big drop gate out back that makes for all sorts of wind resistance going down the road!) for a few days with a couple of lawn mowers on board.

...What I'm trying to say is that it gets used, and between pulling and high-speed runs back to the city (University in Louisville, KY...80+ for 90 miles), I want an oil that protects wonderfully. Always had good experiences with Delo 400, (although girlfriend is having good results with Delvac 1300 Super in a '96 Volvo 850 2.4L 5spd...although that car doesn't tow, it sees alot of high-speed running and that 2.4L I-5 spins some pretty good r.p.m's) so that's why I use 15w-40 Delo in the Lumina.

Anyways, looking at the Lumina's owner manual, it states the following:

5w-30 (yeah, fuel economy!)
10w-30
SAE30

After those three, it says (in bold nontheless), not to use any other grades than those mentioned (Guess I'm breaking the law by running 15w-40).

With that said though, does anyone see any advantages I would have by running a straight 30 weight HDMO over a 15w-40 HDMO in this engine (and yes, I will only use the straight 30 in the warmer months)?

Any disadvantages?


Thanks,

Justin

P.S. - No bad feelings Patman? I just can't resist this site...I'm hooked!! I'm an oil junkie! I promise not to recommend Delo (or other HDMO's) so much anymore.

[ April 09, 2003, 12:31 AM: Message edited by: Justin ]

 

[RobZ71LM7]

You go to UofL? I'm an ME major at Speed School.

 

[Shannow]

Was wondering the same thing on my beater's last oil change.

Why Delvac 15W-40, when the Devac 1330 wasn't much worse cold , and a bit thinner hot. Manual calls for 20W-30 to 20W-50.

With a straight 30, it was unlikely to shear out of grade.

But then I thought the cold temp was 40 degrees C, not -5 degrees C like the forthcoming winter.

Went 15W-40, but may do straight 30 in summer.

 

[Justin]

quote:

---

Originally posted by Shannow:
Was wondering the same thing on my beater's last oil change.

Why Delvac 15W-40, when the Devac 1330 wasn't much worse cold , and a bit thinner hot. Manual calls for 20W-30 to 20W-50.

With a straight 30, it was unlikely to shear out of grade.

But then I thought the cold temp was 40 degrees C, not -5 degrees C like the forthcoming winter.

Went 15W-40, but may do straight 30 in summer.

---

Good to here someone is also pondering this question...now we just need some advice on what to do!

Justin.

 

[Drew99GT]

Your Lumina owners manual actually says SAE straight 30W? That's cool, I'd definetally use that in the summer time over diesel/fleet oil.

 

[Justin]

quote:

---

Originally posted by Drew99GT:
Your Lumina owners manual actually says SAE straight 30W? That's cool, I'd definetally use that in the summer time over diesel/fleet oil.

---

Yep, it says SAE 30 also fine for use, but only above 40 degrees.

Just got back from town where I was trying to find some HDMO SAE 30 (I like the benefits a HDMO over a PCMO!). Couldn't find either Rotella or Delvac in straight 30, but Autozone had a brand new unopened box of 30-weight Delo 400 sitting there...opened it up and grabbed a few gallons.

Funny thing is (well, not too funny), my girlfriend is soooo mad at me. She just can't understand why I am buying more oil when I just changed it not but three weeks ago. She thought I was going to town to get something for her.

Told her "I'm a junkie"

Is there such thing as oil-a-titis (horrible, horrible illness where you spend way too much time discussing oil and too much money buying and testing it)? I think I got it from this site...must be contageous.

Justin.

[ April 09, 2003, 01:47 PM: Message edited by: Justin ]

 

[MolaKule]

Justin,

I would use a synthetic 10W30 such as Amsoil ATM, Mobil 1 10W30 (with Schaeffer's supplement #132), or a blend such as Schaeffer's #703.

The technical papers I have read show how a multivis has less oil consumption issues, and better gas mileage than a straight 30 weight. In my view, a straight weight is only useful where engines are continuosly operating or operating at the same temperature for extended periods of time.

I used to live near Mayfield Kentucky (Murray State U) and this weight of multigrade oil seems to be the best choice for those temperatures.

[ April 09, 2003, 02:04 PM: Message edited by: MolaKule ]

 

[Steve S]

Justin ,good your back the best thing about this internet stuff is we can turn it off and come back later . I totally agree with the heavy duty oil applications. I have posted before that the additive packages of the heavy duty oils are like the premium syn. lubes. I like to call the heavy duty fleet oils synthetic oils with out the synthetic

.These oils are available in 10w30 but usually have to be purchased at an oil distributer which can be found it the phone book. Oil viscosity is chosen by the climate operation takes place in . What need is a 10w oil if you live in the desert and don't take the car out of the area? the 10w oils would get better gas mileage untill the oil warmed up then would there be any difference?

 

[Justin]

quote:

---

Originally posted by Steve S:
Justin ,good your back the best thing about this internet stuff is we can turn it off and come back later . I totally agree with the heavy duty oil applications. I have posted before that the additive packages of the heavy duty oils are like the premium syn. lubes. I like to call the heavy duty fleet oils synthetic oils with out the synthetic

.These oils are available in 10w30 but usually have to be purchased at an oil distributer which can be found it the phone book. Oil viscosity is chosen by the climate operation takes place in . What need is a 10w oil if you live in the desert and don't take the car out of the area? the 10w oils would get better gas mileage untill the oil warmed up then would there be any difference?

---

Cool...someone else who likes the HDMO's!

Basically, I should change my question to this:

Is there any reason that I should dump out the 15w-40 Delo 400 that is in there now, and instead go with the SAE 30 Delo 400 for the summer months?

Here's the two side by side:

Delo 400 SAE 30//Delo 400 15w-40
API Gravity: 28.4/ 29.6
cSt at 40C: 109/ 116
cSt at 100C: 12.1/ 15.6
Viscosity Index: 100/ 134
Flash Point (F: 459/ 446
Pour Point (F: -27/ -38
Sulfated Ash, wt %: 1.61/ 1.5
Base Number, ASTM D 2896: 14/ 12.5
Phosphorus, wt %: 0.119/ 0.136
Zinc, wt%: 0.132/ 0.151

Seems SAE 30 is actually thinner at 40C...hmmmm, I would have thought different
Also, it has a higher flash point. I would have thought the 15w-40 would have had a higher flash point.

Is there any chance that because SAE 30 is much thinner than the 15w-40 at 100C (12.1 vs. 15.6), that it could pump faster providing better protection and less frictional losses?

[ April 09, 2003, 04:30 PM: Message edited by: Justin ]

 

[Justin]

Thanks for the reply MolaKule, but on the other hand, I've never used synthetics before, and I just can't convince myself to use them now (at least in any of my applications). HDMO's have always served me good, and think I'll stick with them for awhile.

Do straight weight oils really have higher consumption rates?? I'm not really concerned about gas mileage (you stated straight weights have lower mileage), I just want the best protection for a reasonable price (either SAE 30 or 15w-40 HDMO)

So you went to Murray State? I'll probably end up going there seeing as they have the only college rodeo team in Kentucky (you'd think different, but most horse people around here are either into racing, dressage, or reining.)

[ April 09, 2003, 04:36 PM: Message edited by: Justin ]

 

[JohnnyG]

Justin, I have been asking all over the place for this answer! I am contemplating the same thing for my Northstar and my boat. There are some that use Delo for boat (gas) engines, but they won't tell me which weight they are using. Delo straight 30 sounds like the perfect summer oil to me! A big concern with most of todays engines and the Northstar in particular is stuck rings from broken down VII. How does the VII content of Delo 400 SAE30 compare to other multigrade oils? As an oil that meets SL specs and is "mixed fleet" I don't see how you can go wrong.

 

[MolaKule]

Justin,

If you intend on using HDMO's, then Schaeffer's 15W40 blend #700 is the best of both worlds.

And yes, the technical papers do prove straight weights cause higher oil consumption.

Most of my relatives still live within 10 miles of where they were born. Mom and Dad live in Cuba, one of my uncle's lives between Cuba and Sedalia, one lives between Mayfield and Pryorsburg, and the other's live in either Lone Oak or Paducah. Mom and Dad live less than 20 minutes from Murray State. I studied mathematics and pre-med at MSU before going to St. Louis. One of my close friends taught mathematics at MSU.

I was the only blacksheep who had the "gumption" to move further west.

[ April 09, 2003, 08:02 PM: Message edited by: MolaKule ]

 

[Justin]

quote:

---

Originally posted by MolaKule:
Justin,

If you intend on using HDMO's, then Schaeffer's 15W40 blend #700 is the best of both worlds.

And yes, the technical papers do prove straight weights cause higher oil consumption.

Most of my relatives still live within 10 miles of where they were born. Mom and Dad live in Cuba, one of my uncle's lives between Cuba and Sedalia, one lives between Mayfield and Pryorsburg, and the other's live in either Lone Oak or Paducah. Mom and Dad live less than 20 minutes from Murray State. I studied mathematics and pre-med at MSU before going to St. Louis. One of my close friends taught mathematics at MSU.

I was the only blacksheep who had the "gumption" to move further west.

---

MolaKule,

I respect your opinions, but could you fill me in on what the numbers of the two oils I previously listed above actually mean in the real world?

Seems like SAE 30 has a lower viscosity at 40C (weird?), as well as a higher flash point (weird again...I would have thought different)

Not dealing with your statement (or the SAE papers statement) for a moment, how do you believe the SAE 30 would protect in this engine: worse, same, or better than the 15w-40?

...Maybe the thinner oil would pump better/easier at operating temperatures, thus providing more oil to the parts that need to be lubricated at any given time???

...Also, isn't it true that straight-weights don't shear down like multi-vis oils?? Seems a SAE 30 could maintain its viscosity and not shear down to a 15w (a la 15w-40) when getting worked hard.

Once again, thanks.

Justin.

[ April 09, 2003, 08:25 PM: Message edited by: Justin ]

 

[YZF150]

Use a multiviscosity oil. Straight weight oil has been overtaken by much better technology. It's no accident that the shelves are 99% stocked with multivis oil.

Straight weights are the oil of choice for lawnmowers.

 

[Calvin]

I dont know if I should say anything here or not as I am not as educated as you guys about this.That said
I will say this.In the area I live with a modest temp range... 40 deg F to 100 deg F..... Honestly I have used straight 30 WT HD oils since the late 1960's.I have used it in every car/truck I have ever had with the exception of my new 2003 Impala that Chevy said I must use 10W-30.

Since it rarely gets very cold here...I can remember it snowing only 2 times since 1962 when I moved here.... I have never had any oil related problems with the many cars I have owned.I have rebuilt many of these engines and some had bearings that looked awsome....I cant honestly say that cold start wear has ever been a real problem.At least I was never able to detect anything with inspecting the engines that I freshened up.

I dont know if this means anything or not...But with my new Impala 3.8V6 I just changed the oil in it for the 1st time...Had about 400 miles on it.I always change my oil with the engine hot....I can say that the 10W-30 that my engine came with from the factory did seem to be thinner and drained differently than my straight 30 HD oils do.I replaced it with Kendall GT1 10W-30 and I will say it pours in like water...The straight sure seems a bit thicker....But it sure didnt drain out like the 30W's that I use.... All I can offer is that observation that even at normal operating temp the multi vis 10W-30 sure seemed thinner while draining than normal 30wt does....

I cant say that means much but if the multi vis 10w-30 should flow like a 30WT when hot this stuff sure didnt seem to.Maybe thats not a valid point.I really came here to try to understand more about these multi vis oils as I have had very limited expirence with them so forgive me if my observation above doesnt help much..

 

[Norm Olt]

If I lived in Hawaii a straight 30W might be an option...

(check out the sunglasses!)

Why would you want to give up all the advantages of a multi-weight HD Fleet-type oil?

Cheers!

 

[Chris A]

I say straight 30, Chevron Supreme.

Looking at it's specs, I'd bet it is always thinner than the typical 15W40 oil with a visc of 15.5/120 @ 100c/40c.

I also don't believe it is "best" to put a oil designed for diesel in a gas auto.

 

[Justin]

quote:

---

Originally posted by Norm Olt:
If I lived in Hawaii a straight 30W might be an option...

(check out the sunglasses!)

Why would you want to give up all the advantages of a multi-weight HD Fleet-type oil?

Cheers!

---

Still wan to use a HDMO, but I'm curious how the straight 30 weight will do (since that's what GM says to use in it)

Off to the auto stores now to see if anyone has Delo or Delvac in straight 30 grade.

 

[Chris A]

quote:

---

Originally posted by Chris A:
I'd bet it is always thinner than the typical 15W40 oil with a visc of 15.5/120 @ 100c/40c.

---

I meant to say that I'd bet it is always thinner > 15f than the typical 15w40 oil ...

[ April 09, 2003, 12:45 PM: Message edited by: Chris A ]

 

[MolaKule]

Well, between the straight 30 weight and the 15W40, if I had to choose between those two I would go with the Delo 15W40 since it appears to have a better AW additive package and a lower pour point.