I still dont get the Diesel oils

[GregH]

ekpolk,
Hold your horses a minute. My question was not meant as a challenge as such. The logic was questioned by me and I still don't buy it as most here don't seem to. I did not in any way mean to be meanspirited. I still think that most IC engines are close enough in operation so that we can dismiss the FM additive as helpful but not absolutley necessary. If my post sounded anything other than a question then I apologize to all that were offended.
GregH

 

[Mamala Bay]

Why not look at the oil analysis from a gasoline engine using a diesel oil.

 

[blsnelling]

My post was an effort to summarize what this post by Molekule. Maybe I got it all wrong. Read it and you be the judge. http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=4;t=000089#000000

 

[G-MAN]

quote:

---

Originally posted by blsnelling:
My post was an effort to summarize what this post by Molekule. Maybe I got it all wrong. Read it and you be the judge.

---

What MK is saying is that with a non-FM oil, your engine is always operating at various points under one of two conditions: fully hydrodynamic, which has the lowest CF, and extreme pressure conditions where the AW/EP additives prevent metal-to-metal contact. When the hydrodynamic film has broken and the AW/EP additives are at work, the CF is at its highest (short of full metal-to-metal contact). Fuel economy is going to be worse with an oil that ALWAYS operates under JUST these two conditions, i.e., full hydrodynamic and AW/EP boundary. You can IMPROVE fuel economy by additing secondary FM additives that DELAY the onset of AW/EP action when the hydrodynamic film breaks down. The CF during the FM transition is in between full hydrodynamic and AW/EP. Hence, an engine that can operate under three levels of CF, .001-.01-.1, will give better fuel economy than one that operates under just two levels, .001-.1. There may be SOME benefit with less wear under this scenario, but it's likely to be very little and the UOAs seem to bear this out.

 

[Schmoe]

Geesh, I never paid enough attention to this stuff while I was taken inorganic chemistry in college...OK, so what makes these transitions occur? Why aren't they all going to be in hydrodynamic film "mode?" Temperature? Oxidation?

 

[blsnelling]

Thanks G-Man II. I took that to mean there was a level of protection missing rather than a level of CF which affects mileage. I like your answer since that means I can still consider oils like Rotella T Synthetic 5w-40 for my gassers. That also explains why I see them recommended here for gas applications. Under normal driving conditions, I doubt that the mileage would be measurably affected anyway.

 

[69 Riv GS]

Diesel oils ARE friction modified. Boron is a FM and AW/EP agent, as are calcium, ZDDP, and moly.

P.S. there's more good info by Molakule - search: "friction modifiers molakule"

Steve

 

[cousincletus]

At work we had a 1995 Dodge 3.9 V6 fullsize truck and they used Drydene Dieselall 15W-40 oil in it from day one. They sold it after over 150,000 miles and the engine still ran well and didn't use any oil. This truck wasn't babied so my belief is that diesel oil will protect at least as well as regular 10W-30, etc.

 

[ekpolk]

quote:

---

Originally posted by GregH:
ekpolk,
Hold your horses a minute. My question was not meant as a challenge as such. The logic was questioned by me and I still don't buy it as most here don't seem to. I did not in any way mean to be meanspirited. I still think that most IC engines are close enough in operation so that we can dismiss the FM additive as helpful but not absolutley necessary. If my post sounded anything other than a question then I apologize to all that were offended.
GregH

---

Greg:

I didn't take it that was; maybe I was the one putting a little too much zing into my post. I only meant "challenge" in the sense of testing the soundness of the information/argument that
is in question. Obviously, for a forum like this to remain effective (and this on plainly is) this should be done in the "let's figure it out" spirit, as opposed to the "let me bludgeon you with my correctness" method. In my book, you were nowhere near bludgeoning with correctness, and I hope I didn't come off that way either.

 

[JohnBrowning]

FM additives also reduce the friction or traction needed by some disel engines valvetrain as I understand it. SO they sacrifice some fuel saveings to insure that the roler in the valve train have enough traction to actualy role. I do not under stand how it is that FM can do this but I am passing this information along any ways.

I have run the Shell Rotella T Synthetic when I was tight on cash and needed an oil change. I do not do extended drains so I am fine with G III oil for the right price. I did not notice anything out of the ordinary while useing it. I think they make a good product but it is not as good as Delvac-1. I also think that competion is increaseing. Delo has a 5W40 as well out now. I belive it is a GIII as well.

 

[Gary Allan]

quote:

---

I think this is another one of those "group think" mentalities on this forum. It's popular to use diesel oils for some reason and I don't think it's backed up by scientific facts.

---

Jumping in a little late here. I don't know about FM and whatnot...but I had pathetic results with M1 in a 10,000 miles UOA ....and vastly improved results with Delvac 1 over the same period. I'd actually like to try the dino diesel oils ..but I don't care for the 15w-40 rating in some of my engines for year 'round use (which one tends to run into with XOCI).

Yes, there is a tendancy for 'group think' on certain oils here. GC for one. You would think that it was the best invention since sliced bread ...but in the terms of "scientific facts" ..HDEO, especially the synths, have proven themselves in XOCI.

In all reality, aside from a particular traight of an engine ..or a particular oil ..most of us are splitting hairs here. Not many ever accumulate the mileage/conditions necessary to challenge the oil to the point where a superior additive or composition package makes a whole lot of difference.

 

[doitmyself]

How oil chemistry has changed in the past 8 years! Up until about 1996, nearly all OTC oils were dual rated. I used to be able to buy diesal rated oil for my Kubota tractor anywhere.

I believe the removal of the C rating back then for gasoline engines was to have cleaner emmisions.