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Can oil type affect EGT?
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Author:  Glend [ Mon Feb 08, 2010 3:58 am ]
Post subject:  Can oil type affect EGT?
Here's one for the technicians! I had my KJ in to Jeep for service today, and as usual I supply my own oil. Up to now I have been using a 5W-40 Semi-Synthetic diesel CI rated oil. This time I decided to swap over to a pure synthetic diesel CI rated oil also a 5W-40. SO the only thing really changing is some additive components and the base construction. On my way home from the service I noticed that my EGT was running hotter than usual, idles at lights hotter, and takes longer to scrub off heat in a cool down cycle in my driveway. The temp difference seems to be around 40F.

So everything else in my Jeep is exactly the same as this morning, and the days before, but the oil, and now I have elevated EGT readings on a pure synthetic. Is this possible? If it is the oil does this not mean more heat stress on the engine and the turbo? I have the properties of both oils and have listed them below:

Old oil (Semi Synthetic API-CI-4 ) : Viscosity Index 153, Base Number 11.9 , Zinc mass 0.110% , Phosp mass 0.101%, Ash mass 1.23%, NOACK Vol mass% 13.0. Density at 15C, kg/l 0.861 .

New Oil (Pure Synthetic with synthetic ester and PAO base oils, API CI-4): Viscosity Index 171, Base Number 12.5, Zinc mass 0.148%, Phosp mass 0.134%, Ash mass 1.62%, NOACK Vol mass% 12.5 . Density at 15C, kg/l 0.867 .

Any ideas or reasons?
Author:  flman [ Mon Feb 08, 2010 7:58 am ]
Post subject:  Re: Can oil type affect EGT?
The synthetic would help with sludge build up in the turbo and return lines, you should not even be using dino oil in a modern OHC diesel. But unless you are driving an 80K tractor trailer, I don't know why you are worried about EGT's any ways? I know some of you haul loads, and it would be nice to have the gauge when you are running the high way, drag racing, or through the tall peaks. Then again, I am sure it is cool to have a pyro 8) Have any of you with gauges ever seen really high EGTs?
Author:  warp2diesel [ Mon Feb 08, 2010 5:38 pm ]
Post subject:  Re: Can oil type affect EGT?
flman wrote:
The synthetic would help with sludge build up in the turbo and return lines, you should not even be using dino oil in a modern OHC diesel. But unless you are driving an 80K tractor trailer, I don't know why you are worried about EGT's any ways? I know some of you haul loads, and it would be nice to have the gauge when you are running the high way, drag racing, or through the tall peaks. Then again, I am sure it is cool to have a pyro 8) Have any of you with gauges ever seen really high EGTs?


The EGT will go through the roof 1400F + if you lock the cruse and let the engine rev (3500-4000 RPM) going up a steep hill. Use your foot and what controls it (like a truck driver does) and drive like your IQ is at least like as high as the temp in F on a warm day, the EGT won't spike. To truckers this is common sense, but with all due respect to Danoid's cohorts at Chrysler, they super blew it on this one and never even ate in a truck stop let alone talked to a truck driver. Having the engine shift down to too low a gear and rev high is stupid. Too bad GDE and the others do not have the encryption crack on the TCM, we have all been wanting it.
Author:  flman [ Mon Feb 08, 2010 5:54 pm ]
Post subject:  Re: Can oil type affect EGT?
warp2diesel wrote:
The EGT will go through the roof 1400F + if you lock the cruse and let the engine rev (3500-4000 RPM) going up a steep hill. Use your foot and what controls it (like a truck driver does) and drive like your IQ is at least like as high as the temp in F on a warm day, the EGT won't spike. To truckers this is common sense, but with all due respect to Danoid's cohorts at Chrysler, they super blew it on this one and never even ate in a truck stop let alone talked to a truck driver. Having the engine shift down to too low a gear and rev high is stupid. Too bad GDE and the others do not have the encryption crack on the TCM, we have all been wanting it.


Never seen the engine even hit 2500 RPM in cruise going up a steep hill. I can only manage to get those RPMs pedal to the metal at a jack rabbit launch. Actually I was going up a steep hill, Highmount NY, up by Belayre Ski center on Friday, and I commented to my wife, "Look, only 1700 RPMs, and we are catching up to all the gassers with their pedal to the metal."
Author:  Glend [ Mon Feb 08, 2010 6:01 pm ]
Post subject:  Re: Can oil type affect EGT?
I am aware of the popular opinions concerning synthetics verses semi-synthetics and pure dino oils. While you may be able to walk into Walmart and buy a good synthetic diesel graded oil (like a CI-4) I have not been able to do that (until very recently). In this country, the majority of available diesel oils are still dino or semis but they do have the additive packages for CI-4. Some people just run petrol based synthetics but these are not a good solution for diesels. Some vehicle importers specifiy the brand oil (like VW). Mobil 1 is not an answer for the CRD as its only CF grade here, and while Delvac is an obvious choice it is not available here (outside of mining towns, and the big transport companies that buy in bulk). We have a very hot climate and anything that impacts temperature management in an engine is something to be considered in engine longevity.

The thermal properties of different oil formulations in bound to affect heat absorption and transfer to the coolant. What my observations was intended to show is that I believe that I am seeing a difference in thermal behaviour between the semi and pure synthetic, and I am seeking advice on the impacts that higher residual heat loads will have on the engine longer term - obviously seals, and the turbo are two areas of concern.

Years ago there was a comparison published of the properties of synthetics and dino oils, heat absorption or thermal transmission were one of the properties measured. I can't find that article now. I am looking for advice on whether the affect that I am seeing in EGT is a result of poorer thermal handling qualities of the synthetic. BTW the coolant temps seem to be marginally higher as well, I need to get my scanner on the bus to be sure of that.
Author:  stoutdog [ Mon Feb 08, 2010 6:03 pm ]
Post subject:  Re: Can oil type affect EGT?
flman wrote:
warp2diesel wrote:
The EGT will go through the roof 1400F + if you lock the cruse and let the engine rev (3500-4000 RPM) going up a steep hill. Use your foot and what controls it (like a truck driver does) and drive like your IQ is at least like as high as the temp in F on a warm day, the EGT won't spike. To truckers this is common sense, but with all due respect to Danoid's cohorts at Chrysler, they super blew it on this one and never even ate in a truck stop let alone talked to a truck driver. Having the engine shift down to too low a gear and rev high is stupid. Too bad GDE and the others do not have the encryption crack on the TCM, we have all been wanting it.


Never seen the engine even hit 2500 RPM in cruise going up a steep hill. I can only manage to get those RPMs pedal to the metal at a jack rabbit launch. Actually I was going up a steep hill, Highmount NY, up by Belayre Ski center on Friday, and I commented to my wife, "Look, only 1700 RPMs, and we are catching up to all the gassers with their pedal to the metal."

That's because you were in O/D lockup, which will be the case 99% of the time. If you were towing up a steep grade, or driving up a REALLY steep grade, and had the cruise control on, your Jeep would most likely downshift in a vain attempt to maintain speed... thus sending your RPMs through the roof.
Author:  flman [ Mon Feb 08, 2010 6:29 pm ]
Post subject:  Re: Can oil type affect EGT?
stoutdog wrote:
That's because you were in O/D lockup, which will be the case 99% of the time. If you were towing up a steep grade, or driving up a REALLY steep grade, and had the cruise control on, your Jeep would most likely downshift in a vain attempt to maintain speed... thus sending your RPMs through the roof.


Exactly, if you are towing, you should have a pyro. But like I asked, before, what kind of EGTs are you guys seeing in the CRDs?
Author:  DarbyWalters [ Mon Feb 08, 2010 6:47 pm ]
Post subject:  Re: Can oil type affect EGT?
Very good questions for this forum: http://bobistheoilguy.com/
Author:  LibertyCRD [ Mon Feb 08, 2010 8:29 pm ]
Post subject:  Re: Can oil type affect EGT?
warp2diesel wrote:
flman wrote:
The synthetic would help with sludge build up in the turbo and return lines, you should not even be using dino oil in a modern OHC diesel. But unless you are driving an 80K tractor trailer, I don't know why you are worried about EGT's any ways? I know some of you haul loads, and it would be nice to have the gauge when you are running the high way, drag racing, or through the tall peaks. Then again, I am sure it is cool to have a pyro 8) Have any of you with gauges ever seen really high EGTs?


The EGT will go through the roof 1400F + if you lock the cruse and let the engine rev (3500-4000 RPM) going up a steep hill. Use your foot and what controls it (like a truck driver does) and drive like your IQ is at least like as high as the temp in F on a warm day, the EGT won't spike. To truckers this is common sense, but with all due respect to Danoid's cohorts at Chrysler, they super blew it on this one and never even ate in a truck stop let alone talked to a truck driver. Having the engine shift down to too low a gear and rev high is stupid. Too bad GDE and the others do not have the encryption crack on the TCM, we have all been wanting it.



I'd love to have seen my EGTs when I was pulling 7,000 lbs. up a 6% grade at 55 MPH with the pedal on the mat through the hills of Tennessee. :jester: Absolutely no issues whatsoever. Guy that bought that CRD from me reports 80K miles on it now and it runs like a top. Either the Shell Rotella is the best oil on the planet, or people worry way too much about EGTs.
Author:  Glend [ Mon Feb 08, 2010 10:48 pm ]
Post subject:  Re: Can oil type affect EGT?
This should probably be required reading for any discussion on turbodiesel oil performance:

http://www.turbodieselregister.com/TDR57_Oil.pdf

Based on the comments in that article (especially on the engineering of Base Stocks and additives) I will probably go back to my semi-synthetic at the next oil change, and accept that I can save money without compromising engine longevity.

Thanks all for the comments.
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