15w-40 vs. Straight 30??

[JonS]

Calvin,
I know what you mean about the 30w being thicker when hot vs. the 10w-30. But, both 30 weights are measured at 212f. This would probably mean that when we drain our oil hot, it could only be at 150f or so. Which is hot to the touch, but a 30 would be thicker at this temp than a 10w-30.

 

[Calvin]

JonS,

Hmm good point....Sure wish I had an oil temp gage on one of my cars.... Maybe next oil change I'll actually put a mech gage probe in the oil and see just what temp it is at.

Thanks.

 

[Chris A]

OK, I'll ask:
Why does a straight wt increase oil consumption?

 

[MolaKule]

Do a search on "multiviscosity." About June or July of last year I had posted some research and eninge results on straight verses mulitweight oils, and how the piston rings "dam-up" oil when traversing the cylinder wall.

I can't locate it right now, but if you do, please post the URL.

 

[jason07-1zzfe]

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=000063

Here's the thread.
But I am confused. In there it sounded like you agreed with Bror who said the straight grades will have lower wear, LESS consumption, but lower mpg and hp also. Which is also what I would think.
If there is a negative to straight grades, than why was it such a selling point of synthetics that they had no VI improver and didn't shear down? I mean if SAE 30 is so bad, Red Line 10w30 is probably worse, in that it would have an even tougher film and less shear

Which I don't believe either (them being worse that is). The only disadvantage I can see is higher viscous drag.

[ April 10, 2003, 11:39 AM: Message edited by: Jason Troxell ]

 

[TooSlick]

Justin,

All best additive/basestock technology goes into the multigrade oils these days. The straight weight stuff is mainly for engines that operate in a very narrow temp range, like stationary engines used indoors, marine inboards that are only used in warm weather and perhaps some farm equipment.

If I was in your position, I'd stick with the Delo 400, 15w-40 in warm to hot weather and I'd use the 5w-30 or 10w-30 Chevron Supreme gas engine oil for colder weather. That should give you the best combination of protection and performance throughout the year.

Even for marine engines, the 15w-40, Group II oils like Delvac 1300 or Delo 400 seem to hold up very well. I saw some tested after 80 hours in a Perkins marine diesel and it didn't shear at all ....

TS

 

[Justin]

quote:

---

Originally posted by TooSlick:
Justin,

All best additive/basestock technology goes into the multigrade oils these days. The straight weight stuff is mainly for engines that operate in a very narrow temp range, like stationary engines used indoors, marine inboards that are only used in warm weather and perhaps some farm equipment.

If I was in your position, I'd stick with the Delo 400, 15w-40 in warm to hot weather and I'd use the 5w-30 or 10w-30 Chevron Supreme gas engine oil for colder weather. That should give you the best combination of protection and performance throughout the year.

Even for marine engines, the 15w-40, Group II oils like Delvac 1300 or Delo 400 seem to hold up very well. I saw some tested after 80 hours in a Perkins marine diesel and it didn't shear at all ....

TS

---

Yeah, I've used 15w-40 Delo in marine inboards with excellent results.

Like I said before, the only reason I want to consider using SAE 30 is because it's right there in the owners manual as a recommended grade (along with 5w-30 and 10w-30), whereas 15w-40 is not.

Maybe I should stick with the 15w-40, but for some reason, I really want to try SAE 30. (I'm obsessed!)

Justin.

 

[MolaKule]

But a recommended grade for what temperature range ? It has to be a narrow range, like early summer to late summer.

[ April 10, 2003, 03:38 PM: Message edited by: MolaKule ]

 

[MolaKule]

Jason, For one narrow temp range, the oil film would be thicker for a 30 weight than for a 10 weight of course. But a 15W40 weight will always have a thicker hydrodynamic oil film on the average than will a straight weight at the range of operating temperatures in question.

For a specific weight of oil at a specific temperature, the thicker oil will always provide for a thicker hydrodynamic film of oil and result in less wear. But that was not the point of the June 13th post.

Here is the point: If you average all temperatures over which the oil is likely to operate, the average wear of metals due to multivis' will be less than for straight weights.

 

[Bror Jace]

I'll agree with a few folks who've stated previously that straight weights have become a niche product which should be used for fairly unusual circumstances where shear stability is a paramount above all other concerns. Maybe agricultural pumps or other machines which are started up and run for many hours at a time at a constant speed.

Straight weights are still available in WalMart and other mass-market merchandizers because old-school dudes will prefer them over a multi-vis oil ... even a good one which will stay in grade for many thousands of miles/hours of operation. My opinion? This stuff is often misapplied. If you surveyed people who bought this stuff, I bet at least 4 out of 5 are using it in an application for which a multi-vis oil would be better suited.

Same goes for non-detergent SA/SB motor oils. This stuff should not be sold in Wal-Mart or the like as it should almost never be used.

Walmart doesn't care about misapplications. They stock what sells. If their customers misuse the products they buy, they don't really care for the most part. And of course most motor oil applications are sufficiently robust/over-engineered that a little misapplication (or even a lot) will never matter.

Jason, when I made those remarks, I was speaking generally and theoretically and I was not aware of the papers and the "damming" effect 'Kule referred to.

Justin a 15W40 should be thicker at operating temp than a straight 30. Only after the 15W40 shears down would they start to equalize ... and you would have to torture Delo 400 to make it shear down even to a 15W30 or so. My guess is it won't go down much more (if any) than that before it would begin to oxidize and thicken.

As for the flashpoint differential, I can't help you.

Oh, and in the interest of making things as complicated as possible, Chevron makes Delo400 in 10W30.

Some other weight to consider for a variety of applications ... including girlfriend's Volvo. Oh, by the way, is that thing a turbo??

The problem with 10W30 Delo400 will be finding it.

I use a straight 40 weight Pennzoil in one application only ... our older snowblower's 10hp B&S single-cylinder, air-cooled, flathead motor. It is kept in a heated garage and has an electric start.

Still, I could probably use a 15W40 in it and never know the difference.

--- Bror Jace

 

[Chris A]

quote:

---

Originally posted by Bror Jace:
If you surveyed people who bought this stuff, I bet at least 4 out of 5 are using it in an application for which a multi-vis oil would be better suited.

Oh, and in the interest of making things as complicated as possible, Chevron makes Delo400 in 10W30.

Some other weight to consider for a variety of applications ... including girlfriend's Volvo. Oh, by the way, is that thing a turbo??

The problem with 10W30 Delo400 will be finding it.

---

I bet if you also polled Delo400 15w40 users and asked which had the lower vis at 0c : Delo400 15w40 or Chevron Supreme straight 30, 4 out of 5 would say the Delo. Wrong.

I'm not trying to push straight weight oil on anyone, but I do think that they have their place in automobiles, especially in the Southern summer climates.

 

[V6 Diesel]

I can give you one example of where a straight 30 weight is recommended by the manufacturer. For my 83 Olds V6 diesel the following grades were called for --
Above 32F to over 100F use 30W, this was preferred
Above 32F to under 100F use 15-40.
Below 60F use 10-30.

For years I would run the 30W in the summer but was a problem when the season changed and I still had 30W in it. I eventually went to running 15-40 year round. Another thing on oil, 20 years ago all 10-30's were diesel rated CC/CD and I notice that was dropped sometime in the past.

[ April 10, 2003, 04:17 PM: Message edited by: V6 Diesel ]

 

[Justin]

Bror Jace: 15w-40 is what will stay in the Volvo unless her and I split and her parents bring it back to the quick lube shop. Looking in the owners manual, it actually says that 15w-40 can be used (also lists 5w-30 and 10w-30) as long as the temperature is above 10 degrees farenheit.

With the way her and I drive though, I want the most protection possible. Right now, it's running Delvac 1300 15w-40 because (instead of my Delo 400) because she liked the black bottle over the blue one (I'm serious!).

BTW, it's a '96 850 2.4L (Naturally Aspirated) 5spd. manual. With the stick and the inline-5, the car is a blast to drive, and it has enough torque to keep the revs low and cruise or, with it's inline/ohc design, you can go screaming down the road and just fly.

On the other hand, my commuting car, a '95 Lumina, is a low-revving design that just kinda lopes down the road...2250rpms at 70, just enough not to shift up and down (automatic..boo!) on the interstate.

It's doesn't see alot of really high-revs, but it does see alot of work, and also gets ran hard.

Even though the manual doesn't spec this oil (15w-40), it runs good with it and I like the much added protection compared to some lube-joint 5w-30.

On the other hand, something like a Delo 400 SAE 30 appeals to me for some strange reason (probably just because it's something different!). Seriously though, I just see that Chevy says that is a recommended grade for it, so that makes me want to try it.

Oh well....enough with this subject. Thanks to all who have replied and given me some advice.

Justin.

 

[RobZ71LM7]

I searched online recently and couldn't find anyone that sold 10w30 Delo and I don't know anyone here that does. I'm interested in trying it out just for fun.

 

[Norm Olt]

Pennzoil LongLife HD 30W is on the shelves in my "neck-o'-the-woods" right next to the 15W-40 and was on sale last week for $1.29 per quart.

There is a difference between a "straight" 30W and a HD30W I presume? Like diesel certification, maybe?

Hell, I'm a believer in multi-weight oils but I think that in the absence of temperature extremes
(not including the internal temperature of the sun & absolute zero)

one oil, well-chosen, ought to do the job on a year-round basis.

IMHO

 

[Flimflam]

quote:

---

Originally posted by 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....

---

Calvin, you are so right. 30-weight is the one to use, my man. I have used 30-weight even in the coldest winters when I lived in New York. No oil-related problems whatsoever. No cold-start wear. I cannot understand all the fuss about cold-weather "pumpability" touted by the Big Oil companies that want to move their multigrades off the shelf.

Yes, I too have observed the multigrades coming out like water at oil change time. I get to thinking, "how can this stuff protect the engine?"


The power of advertising and Mass Media is amazing. Now, even I use multigrades. But mostly in December, January and February, and mostly when I have to take trips to the NorthEast in these cold months.
If you like straight-weights, don't let anyone faze you. Once upon a time, ya'd get in trouble for saying the world is round, when the popular belief was that it was flat.