Oil operating temperature in big-rigs?

[Kernel Potter]

I was wondering since the big rigs have 10 to 15 gallon oil capacities, do they have some sort of oil cooler and thermostat to regulate the oil temp? If they can go anywhere from 10K - 100K+ miles between oil changes they must have to regulate the oil temps depending if they are driven in conditions between sub-freezing stop and go traffic to mountain pulls in 110F+ temps in the desert.

I know in the winter they'll put the radiator covers on the front of the cabs to restrict the cold airflow. Is there anything else done to control oil temps?

 

[BOBISTHEOILGUY]

Actually Kernal, The oil system in a big truck is not much different than other engines. Temps can and is controlled by the cooling system temps and when the engine is engineered, the oil quanity is taken into consideration as to how cool they want it as well before oil has to recirculate. They also can put in a temp control valve but hardly ever would you see this as a variable being used in most engines. I don't think I've seen an oil cooler on one either but I am very limited to what I have seen. I know that on a shrimp boat they use a tube that passes the oil through the water which helps maintain oil cooling. Here is a basic design of a diesel oil lube system to better help show how it works.

[ November 02, 2002, 10:32 AM: Message edited by: BOBISTHEOILGUY ]

 

[Kernel Potter]

Thanks for the info Bob. Great diagram too. I figured with such large oil capacities, very cold weather could keep the oil temps pretty low, increasing moisture build up etc. and needlessly shorten oil change intervals.

 

[MolaKule]

I assume they have an oil channel in the crankshaft that pressurizes the con rod
or "big-end" bearing.

[ November 04, 2002, 02:01 PM: Message edited by: MolaKule ]

 

[mrchecker]

Diesel engines typically have a water to oil oil cooler. On the diagram Bob posted this can be seen as the long tube perpendicular to the oil filter. The oil cooler functions as an oil heater when the coolant temp is higher than the oil temp. A heavy truck will typically have the oil temp within 10 degrees of the coolant temp once the engine is warmed up.

[ May 18, 2003, 12:35 PM: Message edited by: mrchecker ]

 

[Chris142]

quote:

---

Originally posted by mrchecker:
Diesel engines typically have a water to oil oil cooler. On the diagram Bob posted this can be seen as the long tube perpendicular to the oil filter. The oil cooler functions as an oil heater when the coolant temp is higher than the oil temp. A heavy truck will typically have the oil temp within 10 degrees of the coolant temp once the engine is warmed up.

---

Untill you pull a hill. I used to go up cajon pass loaded to 80k daily. The water temp stayed around 200 deg but the oil temp would go past 250 deg, never hit the 300 deg though.

 

[Doug Hillary]

Hi,

I own a small fleet of Detroit Diesel DDEC4 500hp powered heavy trucks (GVW 45000 kg). The oil temperature is quite constant due to good oil system management on this engine

• The programmed engine shutdown is @120C oil temp
  A "Warning" is given @115C oil temp
  Normal is rated as li>

• 
  The highest temperature reached in climbing ( high mountain range ) in my vehicles has been 112C oil temp
  The "normal" flat running temperature on my vehicles is about 95C oil temp
  
  I use Mobil Delvac 1 5w-40 with Donaldson ELF3998 filters and a Glacier-Mann by-pass centrifuge. The oil is changed every 100000kms (62000 miles)
  By sampling we know that the viscosity remains within spec, and that the centrifuge removes most soot. The TAN/TBN ratio is still within acceptable limits too
  
  Normal operating Ambient Temperature range is :
  • winter -5C to 30C
    summer 11C to 42C
  
  Regards
  Doug Hillary
  Airlie Beach - Tropical North Queensland - Australia
  MY02 Subaru Outback 2.5
  MY98 BMW Z3 2.8
  MY89 Porsche 928S4

 

[msparks]

quote:

---

Originally posted by Doug Hillary:
Hi,

• The programmed engine shutdown is @120C oil temp
  A "Warning" is given @115C oil temp
  Normal is rated as li>

• 
  The highest temperature reached in climbing ( high mountain range ) in my vehicles has been 112C oil temp
  The "normal" flat running temperature on my vehicles is about 95C oil temp
  
  I use Mobil Delvac 1 5w-40 with Donaldson ELF3998 filters and a Glacier-Mann by-pass centrifuge.

• ---

• Boy I would hate to see the temps you would get with a conventional lube. I bet then would be a good 10-20 degree(C) than that!!
  
  Sounds like you have a very effective engine management program!!

 

[Doug Hillary]

Hi,

I changed from mineral Castrol RX Super to a Castrol semi-synthetic Enduro LD about 10 years ago and to Delvac 1 about 3 years ago
In Australia it is possible that a truck could experience a temperature variance of from -5 to 30 in an overnight journey of 600+ miles
I would never operate a truck without synthetic engine, transmission and diff oils. I use 75W-90 Mobil SHC or Castrol Syntrax 75w-90 in diffs instead of 80w-140 due to the temperature variances

Regards
Doug Hillary

 

[sprintman]

Doug you should investigate Redline gear oils for your fleet which are far superior to the Mobil stuff IMO.