What temperature is too hot for conventional oil?

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The initial oxidation increase of fully synthetic oils could be higher than semis, because the lack of hc molecule branches that help specially in dispersion (that's why the mineral oil content is good to combat lead sludge in avgas), but in the long run, syn stabilizes first and supersedes the semi that keep going up and up, specially at very high temperatures. Modern conventional is keeping its viscosity better now from the add pack, that should be tougher to keep up than that in synthetics. But once depleted, the thing hit the fan and buildup shows up quickier. Isn't it?
 
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Full synthetic all the way. That is inhospitable environment to anything engineered by humans, and you want best possible protection.
 
Originally Posted By: JustinH
I might consider a transmission cooler to keep the temp of the trans fluid as low as you can.


The transmission already has a cooler and is thermostatically controlled, this is the temp Ford wants it to run.

I had to look up the flash point of the 10w-30 I run (Deere Plus 50 II 10w-30), its 223C, which converts to 433.4F! Just sit back and enjoy your truck as you are within the parameters for which its designed to run.
 
IIRC, GM created their 4718M (high temp) spec because of the packaging design limitations on earlier C4 and C5 Vettes. They were enduring track temps around 300 and needed a better oil to fight burnoff and oxidation. I wouldn't be concerned about
Fill it with the OEM recommended oil and let the oil life monitor sort it out.
 
Originally Posted By: roadrunner1
Originally Posted By: JustinH
I might consider a transmission cooler to keep the temp of the trans fluid as low as you can.


The transmission already has a cooler and is thermostatically controlled, this is the temp Ford wants it to run.

I had to look up the flash point of the 10w-30 I run (Deere Plus 50 II 10w-30), its 223C, which converts to 433.4F! Just sit back and enjoy your truck as you are within the parameters for which its designed to run.

Not any different then full synthetic oil. However, flash point does not give any indication whether oil will "break" under load or properly protect engine.
Also, turbo's are running much hotter then 433.4f.
 
The Corvette always pops up in these oil temperature threads.

The service engine oil grade is 5W30, but for track use, GM recommends 15W50.
The heavier grade will create more heat due to fluid friction and raise the sump/bulk oil temperature.
With 5W30 operating at high sump temperature, the oil pressure may be lower than 15W50.
Lower oil pressure brings with it less flow to the engine, not dependent on the position of the pump relief.
Thicker 15W50 running at a higher sump temperature, will dissipate more heat to ambient,
while providing an increased level of protection to the bearings.
 
Originally Posted By: roadrunner1
Everything in your truck is thermostatically controlled (same as mine) you have nothing to be concerned with. Your turbo is coolant cooled as is almost everything else built this century, so no concerns with over heating turbo bearings. The thermostats are set in the 6.7 so not to overheat anything using CJ-4 specced lube.

Check one of my UOA's with 10w-30 in my 6.7, I have seen regular temps at the thermostat in/out temp and I run to the IOLM limit.

If it makes you sleep better at night switch to a syn, but quite honestly your truck could care less, Ford engineers spent countless hours ensuring that a CJ-4 lube and the 6.7 would be just fine together, not a syn CJ-4, any oil meeting CJ-4 spec.
If all of that is true, what does it take so little for Ford to say use a 5W-40 which is only available in synthetic? Towing, high speed operation, use of biodiesel, operation in high heat, etc. Something does not quite add up.
 
Originally Posted By: 2015_PSD
I totally agree we have the same concerns, no worries there. I was simply thinking (which could be totally wtong) that OTRs have more reserve capacity than light duties do. I am just not sure about using a conventional oil at 240F over a prolonged periods of time. Varnish, sludging, and bearing coking are my concerns.


Pick-ups have a higher power density (more power vs less weight). They also have a smaller lubricating systems. BUT, big rigs pull for much longer at 80,000. Some of those grades that a pick-up and boat will get over in 1/2 hour, will take a big rig fully laden a hour to climb. So the capacities sort of even out.

The big question is how fast can the oil coolers transfer heat? On a big rig, they have a lot of transfer ability (except for the Volvo, and that seemed a control issue...). Pickups MAY have less oil cooling capacity...

So is anyone running a Pyro anymore? Back in the day, we always lived by exhaust gas temps at the turbo when climbing. 1,200* was the running limit on a well cooled motor. Cross that boundary for more than a few minutes and you were walking sooner, rather than later ...

Those temps translate into turbo housing temps or 900* and that's hot enough to fry even synthetic oils. So then you want to know the flow rate through the turbo so you know how long it is exposed to that temp?

There is a reason Shell brought out Rotella T6, and Chevron went to Iso-Syn for Delo 400. Modern motors run hotter for fuel efficiency (big rigs & pickups). Heat IS power. Gone are the days of 180* cooling systems. So the need is there for better oils. And the refiners have answered the call. Modern oils work.

But you still gotta watch the turbo temps. It just comes with owning the beasts and pulling grades
laugh.gif
 
Originally Posted By: 2015_PSD
It did make me wonder what the temps would have been had I been towing. What would be considered the temperature limit for conventional CJ-4 oil? Can it handle 240F under sustained conditions? Any consideration for the turbo? I am (and have been) running either a synthetic 5W-40 or a SynBlend 15W-40. Thanks for your thoughts!

I understand your alarm. The engine found in the G37 and 370Z sees some ridiculous oil temperatures even during some fairly pedestrian running. But, I would gather the OEMs have an idea of what they're doing.

I think you'd be fine, and others with OTR experience have already chimed in. It would be nice if Doug would wander through this thread. Are you still using the Delvac 1 in your signature, by the way? I know you were talking about switching, but I don't know if you've gotten to that point yet.
 
Originally Posted By: Garak
It would be nice if Doug would wander through this thread. Are you still using the Delvac 1 in your signature, by the way? I know you were talking about switching, but I don't know if you've gotten to that point yet.
Delvac 1 is in the sump now.
 
Was planning on looking into using Schaffers 10w-30 per tired truckers (I think) recommendation, but the Mobil Delvac ESP 5w-40 sale allowed me to stock up again. 2015_PSD, (I know not scientific), but what do you mean by the Kendall 15w-40 felt smoother than Mobil Delvac 5w-40? Lots of great stuff...thanks to all for sharing your knowledge.
 
Originally Posted By: mbacfp
2015_PSD, (I know not scientific), but what do you mean by the Kendall 15w-40 felt smoother than Mobil Delvac 5w-40? Lots of great stuff...thanks to all for sharing your knowledge.
The engine was quieter on Kendall versus MC 10W-30, Delo 400 LE 5W-40, and Rotella T6 5W-40. It is really close between the Delvac that is in it now and Kendall. This is all seat of the pants, of course, but of all the oils I have tried T6 was the noisiest. Keep in mind, these 6.7L engines are far and away quieter than diesels of yesteryear. Delvac ESP is expensive in my area and I bought 16 gallons on a black Friday special at Pepboys. When I run out, I will either use Kendall 15W-40 SynBlend or Delo 400 LE 5W-40 Synthetic. Hope this helps.
 
Originally Posted By: BrocLuno
Originally Posted By: 2015_PSD
I totally agree we have the same concerns, no worries there. I was simply thinking (which could be totally wtong) that OTRs have more reserve capacity than light duties do. I am just not sure about using a conventional oil at 240F over a prolonged periods of time. Varnish, sludging, and bearing coking are my concerns.


Pick-ups have a higher power density (more power vs less weight). They also have a smaller lubricating systems. BUT, big rigs pull for much longer at 80,000. Some of those grades that a pick-up and boat will get over in 1/2 hour, will take a big rig fully laden a hour to climb. So the capacities sort of even out.

The big question is how fast can the oil coolers transfer heat? On a big rig, they have a lot of transfer ability (except for the Volvo, and that seemed a control issue...). Pickups MAY have less oil cooling capacity...

So is anyone running a Pyro anymore? Back in the day, we always lived by exhaust gas temps at the turbo when climbing. 1,200* was the running limit on a well cooled motor. Cross that boundary for more than a few minutes and you were walking sooner, rather than later ...

Those temps translate into turbo housing temps or 900* and that's hot enough to fry even synthetic oils. So then you want to know the flow rate through the turbo so you know how long it is exposed to that temp?

There is a reason Shell brought out Rotella T6, and Chevron went to Iso-Syn for Delo 400. Modern motors run hotter for fuel efficiency (big rigs & pickups). Heat IS power. Gone are the days of 180* cooling systems. So the need is there for better oils. And the refiners have answered the call. Modern oils work.

But you still gotta watch the turbo temps. It just comes with owning the beasts and pulling grades
laugh.gif

I have seen 1400F EGTs (wish I would have had my TorquePro connected this time) on my PSD before, I think these things run hot!
 
Thanks for sharing your experience. I've heard that same thing about Rotella T6 from others. Does that mean anything? Probably not...but I agree with your ordering of oils. Maybe someone can chime in...what about an oil that could possibly make an engine sound different in comparison to others? Fairly or unfairly, I've personally stayed away from using T6...went with Valvoline Premium Blue 5w-40 and now Delvac 5w-40 (could not tell any difference between those two oils).
 
Last week I posted Petro-Canada, Vanderbilt and Lubrizol links.
All said the same as Chevron except with the words in a different order.
Next day, this thread.
 
2015_PSD, have you noticed any difference in regen frequency between those oils? Thanks.
 
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