Short Trips - Severe Service Definition

[texasproud]

Tons of threads on Old Lady drivers and short trips considered as "severe service". I make short trips almost daily (less than 2 miles) and my temp gauge comes up to normal operating temp fairly quickly, usually in a couple of blocks. I assume my oil is at operating temp as well. Does it take longer for engine oil to come up to operating temp than it does coolant ?

If the answer is yes....does it not make more sense to change the thermostat to one that opens slower rather than increase the OCIs or run synthetic ?

If the answer is "NO" how much longer does it take for the oil to come up to temp so as to burn off condensation ?

BTW: I realize Texas is different than Mn in winter.

 

[AndyH]

quote:

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Originally posted by texasproud:
Tons of threads on Old Lady drivers and short trips considered as "severe service". I make short trips almost daily (less than 2 miles) and my temp gauge comes up to normal operating temp fairly quickly, usually in a couple of blocks. I assume my oil is at operating temp as well. Does it take longer for engine oil to come up to operating temp than it does coolant ?

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No, just because your coolant-temp gauge reads "normal" does not mean that the oil is up to normal operating temps.

quote:

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Originally posted by texasproud:
If the answer is "NO" how much longer does it take for the oil to come up to temp so as to burn off condensation ?

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Perhaps 15 minutes or so...probably depends on a number of factors such as ambient temperature, sump capacity, etc.

 

[mechtech]

Oil and water temps are separate.
Water is heated primarily from the head.
Oil is heated primarily from the piston bottoms.
Putting in a higher temp therm may make your sensors put the fan on all the time, and pull timing from the ECU.
Use a light oil for short trip vehicles.

 

[Gary Allan]

The only thing that I can think of that would help your situation is a heat exchanger ..but in a two mile commute, I doubt that you're gonna get enough of an increase to make that much of a difference. What are you driving, anyway? I didn't see it in your post. For all we know ..you already have one.

 

[texasproud]

Thanks for the info. I would have thought oil & water are both circulated thru the block and would heat/cool at the same rate. Interesting information.

BTW, I drive a Silverado 2500HD with 6 liter gas motor. I do not consider it severe service because it gets on the highway daily as well. I was just curious about the definition of "short run...severe service" as a possible solution to the "It's my Mom's car".

 

[Palut]

In my car, the water temperature gauge hits the normal mark within 2 miles of driving, the oil doesn't get up to temp until I've driven 8-10 miles.

 

[Ray H]

Even if the same volume of motor oil flowed through the engine block galleries as the volume of coolant through the coolant passages, motor oil still has a lower specific heat index than coolant. It simply takes longer for motor oil to come up to a given temperature. (and correspondingly longer to cool back down) At just two miles per commute, you'd best assume your engine is seeing "severe service".

Three of the most oft-cited definitions of "severe service" are:
1> driving less than 5 miles per trip
2> driving in hot conditions (>90 degrees F.)
3> driving in windy/dusty conditions

You've already indicated you routinely operate your truck well within the first condition. Do either of the remaining conditions occur in Texas?

 

[texasproud]

Ray,

I would say that all three of your severe service conditions are prevelant in Texas. We see 90 degree days for sometimes 6 months at a time. Although dust is not much of a problem on the highway...we experience a lot of dust on rural roads. Real fine "Caliche" dust...I bet it is a killer if it makes it by the air filter !!

 

[Tree Hugger]

Do you have the Oil Life Monitor in your Silverado? It's estimate of OCI would be an accurate assesment of whether your service is 'severe'.

 

[martyi]

My Honda has an OLM that is similar to GMs. I believe it can track short trip/cold start via calculations as to engine temps and revolutions. I am not exactly sure how it works but all the things I've read seem to indicate an OLM (not a mileage or idiot light type device) is a more accurate indicator for OCI than some arbitrary figure like 3,000 miles/3 months.

However, there are some things the OLM can not know that may impact on your service requirements. For example, heavy towing and dusty conditions will stress the vehicle but how does the OLM know? Also, most OLMs are programmed for dino oil that meets certain factory specs. What if you use synthetics that should last much longer? The OLM does not know what kind of oil you use nor does it know if you top off or use additives like LC20. These things rejuvenate the oil and so the oil life expectancy shown may not be accurate.

I think that if the severe service is of a factor not able to be recognized by the OLM, you need to change more frequently than actually indicated on the service due notice. Of course, in all instances, it is best to check your driving habits and OLM services notices with a periodic UOA. This is probably the best way to determine if your driving habits are in sync with what the OLM is telling you.

 

[Mitch Alsup]

I need to expand on this:

quote:

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Originally posted by texasproud:
Ray,

I would say that all three of your severe service conditions are prevelant in Texas. We see 90 degree days for sometimes 6 months at a time.

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That is, for 3 months of the year it does not ever get below 90 degrees; even just before daybreak. Durring this period, daytime minimum temperature is always greater than 90dF.

And there are more than 180 days each year that it gets above 90dF.

 

[Schism]

quote:

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Originally posted by martyi:


However, there are some things the OLM can not know that may impact on your service requirements. For example, heavy towing and dusty conditions will stress the vehicle but how does the OLM know?

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The OLM should compensate for the "load"(stress) on the engine when towing. The ECU knows this, and it should be forwarded to the OLM. You can even get a device that plugs into a modern truck to see what % of load your motor was under while driving.

 

[LarryL]

Short trips and dust are severe condition but driving in >90F temps is just fine if your car is in good condition. The insides of the engine don't see much of the warm weather and you engine might just warm up quicker, which is good. Your cooling system works fine in hot temps if it's working like designed. Low temps would be a problem. It takes longer to warm up and of cource really cold weather can be a challange for all the systems in a car and should be classified as severe.

 

[Hokiefyd]

The OLM does know the "load" on your engine. The GMOLM does anyway. I'm not sure how Honda's works.

And you're right...if you add make up oil, that's only going to theoretically extend your OCI by an incremental amount, so the OLM will be on the conservative side -- where you want it to be.

Following the OLM is the way to go no matter what. If your trips are short enough and the weather cold enough, it'll call for an oil change BEFORE that "magic" 3000 mile mark. Under many circumstances, though, 3000 miles is way too soon. The OLM was engineered for your particular engine, and it will be the most accurate indicator of what your particular OCI should be, on that particlar oil change.

 

[Patman]

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Originally posted by Jason Adcock:
The OLM does know the "load" on your engine. The GMOLM does anyway. I'm not sure how Honda's works.

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Actually I do not believe the GM OLM would know when the engine is under load. It goes by rpm and temperature, so if you're keeping your rpms low, but pulling a heavy load, the monitor is going to think the engine is not being stressed. Only if you see a lot of high rpms will it count down quicker.

 

[yugrus]

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Originally posted by Patman:
It goes by rpm and temperature...

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Does it not go by the throttle position sensor and manifold absolute pressure readings as well? ScanGauge calculates engine load very well...

 

[Zaedock]

quote:

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Originally posted by yugrus:

quote:

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Originally posted by Patman:
It goes by rpm and temperature...

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Does it not go by the throttle position sensor and manifold absolute pressure readings as well? ScanGauge calculates engine load very well...

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I'm sure it takes all engine variables into account (TPS,CTS,MAP,engine RPM, the duration the fuel injectors are open). It's all thrown into the calculation.
The only way to know for sure, would to become a GM engineer to gain access to proprietory info. If you don't have proper access, the GM Ninja's will drop from the trees and take you away.

 

[CONMCK]

Patman,
the fact that the engine is under load regardless of RPM should elevate the engine oil tempurature, would it not? Whether the engine is turning 1500 rpm vs 2500 rpm, it still has to produce the same amount of power;
if anything the lower rpm may even elevate temps more (less air & coolant circulation).

I guess the fact that the engine is turning at a slower RPM should result in a slower countdown

This is something I need consider myself, I'll admit I don't hesitate to tow in drive (01 gmc 1/2 ton 4X4 ECSB) even with light tow loads where maybe it's not required and maybe my OCI light wouldn't come on so soon sometimes.

 

[brianl703]

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Originally posted by yugrus:
ScanGauge calculates engine load very well...

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I don't think the ScanGauge calculates engine load..the ECU does that and sends the values to the ScanGauge.

 

[92saturnsl2]

The GM OLM does monitor engine load by using the manifold absolute pressure sensor (MAP) in vehicles so equipped, or the mass air flow sensor. By combining that value with the engine RPM, load is calculated and relayed to the ECU, which in turn uses that to calculate the oil life.

I got the information out of a '02 Saturn L300 service manual, this of course being for the 2.2L Ecotec engine, however I'm fairly certain all GM's OLM uses engine load as a variable.