Not another synthetic oil question...

[4x4man]

Long time lurker, first time posting.
I have done numerous searches to try and answer my own questions, although I have learned a lot, I wasn't able to find the answers I was looking for..maybe wrong buzz words.

I have a 2003 Duramax Diesel getting close to 20,000 miles and ready for another oil change. This engine is non EGR, no CAT, 10 quart oil capacity, water cooled turbo. I use it to tow our 5er (10,000 lbs) about once or twice a month average. I am currently using Delo 400 15w40 and changing every 5,000 miles, even though GM owners manual states follow the oil life monitor, which seems to be averaging about 10-11,000 miles in my case.

Here is my question. I am trying to find out if and/or why I should use synthetic oil in my Duramax. I understand the benefits in the cold, but trying to figure out the other extreme, heat. It seems, from what I have read, that the flash point determines when the oil will coke, Delvac 1 is 438F, Delo 400 is 446F, Delvac 1300 is also 446F. There obviously has to be something else I am missing as it doesn't look like there is a benefit, but can't figure it out. Any help or insite would be appreciated.
Thanks,
Bob

 

[TooSlick]

Flash point really isn't a good measure of merit in this case.... The PAO/Ester basestocks used in high end synthetic lubes don't leave any carbon residue when they thermally decompose.

Take two ounce samples of Delvac 1 and Delvac 1300 and put them in small aluminum muffin tins, then cook them on the grill - with the cover up - for 30 minutes at high heat. Note: turn down the heat when the conventional oil starts to smoke.

What you'll see is that the conventional oil leaves carbon and varnish residues in the tin after it cools down, but the synthetic will simply darken by one or two shades.

 

[buster]

quote:

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I am trying to find out if and/or why I should use synthetic oil in my Duramax

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If you do I'd go with Amsoil Series 3000/Delvac 1. S3k will give better mpg. A friend of a friend has the Duramax and goes 15k miles on S3k and the oil has plenty of life left.

 

[Steve S]

It would be hard to see any real gains in wear or fuel consumption in real life by changing to a syn oil . The new heavy duty oils are long life as is and would probably go the oil moniter interval with results equal to the over priced syn oils. But for cold weather lets say below 20 f syn oil would be the way to go. When pao base stock burns it leaves a hard residue but in real life there doesn't seem to be a problem.

[ April 07, 2004, 10:55 PM: Message edited by: Steve S ]

 

[4x4man]

Thanks for the responses so far. I have thought about taking the Delo out to 10k and have it analized to see if it holds up or not and post it for the group to comment on. But gosh that is a long time to go on conventional oil!! At least GM can't void my warranty for a 10k drain as that is what they want...
May just give George a call at Avlube and take the plunge, or check out the new Mobil 1 Truck/SUV.. After all my Exhaust temps coming out the manifold have been up to 1300 degrees pulling grades in Colorado, I'm sure the turbo and under the crown of the pistons are rather hot and killer on the oil.
Bob

 

[toyvwbenz]

quote:

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Take two ounce samples of Delvac 1 and Delvac 1300 and put them in small aluminum muffin tins, then cook them on the grill - with the cover up - for 30 minutes at high heat. Note: turn down the heat when the conventional oil starts to smoke.

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Tooslick, it's interesting that you would bring this up. I assume you are referring to the oil BBQ done over at the TDIClub. This was a very unscientific test. The oil samples in the center of the grill took most of the heat and it just so happened the Delvac 1 sample was on the outside of the grill. The Delvac 1300 was on the center of the grill, no surprise that it burned. However, there was a second test using tile to distribute the heat more evenly. The Delvac 1300 did not appear to be more degraded than the Delvac 1. In fact the person conducting the test said that it appeared the 1300 sample outperformed Delvac 1. A quick search at the TDIClub and you can see for yourself.

 

[Eiron]

4x4man,

With everything I've learned about synthetics, I'd say switch from the dino Delo to Shell's Rotella T syn 5W-40 or the new Mobil 1 5W-40 (purely for cost reasons over the D1) & start following the OLM. This will still fall way short of what the oil is capable of, but it will give you plenty of peace-of-mind & a little extra time due to fewer oil changes.

Glad to have you with us!

 

[Pablo]

It would be interesting to run a used oil analysis of the Delo at 10K. I'll bet it may be pretty tired.....whereas a good syn should carry you to 10K - 20K, easily. That's the main difference.

 

[Dick in Falls Church]

Ok, you don't like the grill test, too unscientific.

How about the NOACK Volatility Test?

Delvac 1300 is 15.65%, tested March 2003.

Don't have Delvac 1 figures on hand, but suspect it would be lower.

 

[davidc]

quote:

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Originally posted by Steve S:
It would be hard to see any real gains in wear or fuel consumption in real life by changing to a syn oil . The new heavy duty oils are long life as is and would probably go the oil moniter interval with results equal to the over priced syn oils. But for cold weather lets say below 20 f syn oil would be the way to go. When pao base stock burns it leaves a hard residue but in real life there doesn't seem to be a problem.

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Contrary to your statement, I was able to quantify a 7% increase in my average fuel economy on my first diesel (70K worth) when I changed from conventional 15W40 to a high performance synthetic 15W40. As I learned about the capability of the high performance oil, I also increased my drain intervals over teh next 100,000 miles.

I disagree that you can not quantify significant results.

 

[4x4man]

Again, thanks for the additional comments. I did find the BBQ test this afternoon and found it interesting, wish I knew how hot that oil got!! Obviously running 1300 EGT's doesn't actually heat up the oil to that temp or else it would turn into a chared solid clump!! I guess when you look at the numbers, $1.75qt for Delo * 10 qts plus $15 for the oil filter comes to $32.50 every 5k. So $65 for two changes in 10k miles. With Mobil 1 Truck and SUV at $5 qt * 10 qts plus $15 for the oil filter is $65. A wash.

So I guess being at 20k, I shouldn't have any problems switching over to synthetic. Might as well enjoy the extra benefits of sythetic for basically the same price!! Guess I just didn't put two and two together...thanks again for all info as I am still in the learning phase.
Bob

 

[TooSlick]

DavidC,

We'd love to have Royal Purple as a site sponsor - you need to pony up the $$$ and quit lurking ...

Besides, I need to pick your brain about this "Synerlec" stuff.

TS

 

[toyvwbenz]

quote:

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Delvac 1300 is 15.65%, tested March 2003.

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****,

The last specs I saw Delvac 1 and 1300 were very close at around 13.5%. Now I can't remember where I found it. If I'm not mistaken, CI-4 requires
Here is an interesting link to an independant evaporative loss experiment. Delvac 1 performed very poorly. Got whipped by group II and III oils.

 

[Dick in Falls Church]

NOACK Volatility test for Delvac 1300 was (horrors) on an AMSOIL brochure re: diesel oils.

 

[toyvwbenz]

quote:

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Testing at this higher temp is much more relevant in terms of quantifying oil consumption in actual service and comparing the thermal stability of various oils.

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I guess you will have to explain this one to me. I would think that testing at a lower temp of say 300F would be more relevant. Typical sump temps are about 200-250F. If the oil never sees 482F why would it be relevant. Yea, some say the oil in the rings gets this hot, but I have to wonder.

I found it interesting that the beloved Delvac 1 performed so poorly. Maybe it begins to shine when the temperature gets to 482F. Maybe it's NOACK numbers just aren't that good. Fact is, Delvac 1 got beat by group II and III oils at 400F. For the price you pay for Delvac 1 it should do better.

 

[TooSlick]

The test on the TDI site was performed @ only 400F , which is significantly BELOW the flash point of even conventional oils.

The Noack volatility test is performed @ 250C/482F - specifically because this is higher than the flash point of even synthetic oils like Redline. Testing at this higher temp is much more relevant in terms of quantifying oil consumption in actual service and comparing the thermal stability of various oils.

Of course, some lab tech on the TDI list could simply be smarter than the API,SAE and ASTM combined, when it comes to designing an experiment?

Tooslick
Dixie Synthetics

 

[Eiron]

Group beatings for going off-topic?? Heck, we'd have a total of about four posts if things stayed on-track around here! O/T is what keeps things lively & introduces a ton of fresh info!

 

[vonTrapp]

LOL!

Just worried me with those temps!

ps I love the

avatar! I gotta steal that for my other forums!

 

[tdi-rick]

Far'n farenheit, wish you blokes would talk in international SI units.

I had to get my conversion chart out to see what it all meant.

Hmmm, 1300* F = approx. 705* C. I suppose a lot depends on where the temp. is measured. If it's before the turbo, in the exhaust manifold, I've been told thats really about the upper limit, with about 750*C starting to cause damage,
but if it was measured after the turbo in the dump pipe............I'd be a bit concerned.
FWIW, I've only had a pyro in one of our vehicles for a week, and I've already measured 612*C (1135*F). I wonder where it would end up under serious load towing, and the fueling is bog stock. (Land Rover Tdi)

Rick

 

[XS650]

quote:

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Originally posted by vonTrapp:

quote:

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Originally posted by 4x4man:
After all my Exhaust temps coming out the manifold have been up to 1300 degrees pulling grades in Colorado

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Sorry, but I had to point something out

1300 Deg on your pyro??? That seems DANGEROUSLY high! Have you done some mods to that Duramax (like upping the fuel delivery)?

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1300 F is a reasonable exhaust temp in the manifold.

http://www.bankspower.com/Tech_whyegt.cfm