Short trips?

[Chris B.]

What is considered a short trip? I drive about 6 miles to work and reach full operating temp befor I get there. It takes me about 10-12 minutes to make the trip and most of that I'll be doing 45-55 mph. Would a trip like this be considered a "short" trip? and why is a short trip hard on an oil? Thanks!

 

[Patman]

Short trips are hard on the oil because the moisture doesn't get fully burned off, so sludge becomes a factor. The definition of a short trip will be different for different cars and for different ambient temps too. For instance, a small engine with a small cooling system will warm up very fast, such as my wife's Honda, which even on the coldest morning will still warm up in only about 3 miles, while my Firebird takes more than twice that distance. Also, in the summertime, you can cut those distances in half yet again. So someone with a small car doing a 3 mile trip in the summertime is going to be in a better position than someone with a big car doing a 6 mile trip in the winter. Suffice to say that if you do 20 mile trips, you're more than safe, no matter what the car or weather conditions. I'm glad that my trip to work is 25 miles each way (and with rush hour the oil really gets hot!)

 

[Mike Thompson]

When living in Alaska, my old GF had a civic. It wouldn't warm up anywhere below 0F, had to put cardboard on the radiator mostly to block airflow around the engine. My Saab turbo, on the other hand, warmed up quickly no matter what. Heated seats were nice............ Mike

 

[Spector]

Well, you also need to define warm up. Just because the temp gauge has reached the normal area for the car does not mean that the "oil" has reached the really hot temp that it would in a 20 mile trip and burn that condensation off. To me anything under 10 miles regardless of engine is a SHORT trip. Unless you have an oil temp gauge to show that the coolan ttemp is the same as the oil temp then I vote for 10 + miles as a minimum

 

[TooSlick]

Chris, I have factory installed oil temp and oil pressure gauges in my Audi 100 sedan. When the temps are below freezing it takes 10-12 miles for the oil to come to an equilibrium temp of about 190F. I'd say any trip less than ten miles clearly falls into the severe service catagory, particularly in the winter. You will get more fuel dilution, moisture and general oil contamination under these conditions. Some of these newer hypereutectic (sic) aluminum pistons are quite loose in the cylinders when the engine is cold, hence the piston slap you see discussed. This also means you are getting more "blowby" while the engine is warming up. I'd reduce the oil change interval by 50% for a commute of less than 10 miles .... TooSlick

 

[Patman]

quote:

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Originally posted by Spector: Well, you also need to define warm up. Just because the temp gauge has reached the normal area for the car does not mean that the "oil" has reached the really hot temp that it would in a 20 mile trip and burn that condensation off. To me anything under 10 miles regardless of engine is a SHORT trip. Unless you have an oil temp gauge to show that the coolan ttemp is the same as the oil temp then I vote for 10 + miles as a minimum

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Good point! When I mentioned the warm up points on my two cars, that was strictly coolant temperature, as I don't have oil temperature gauges to give totally accurate info. But I do realize that it will take a few more miles after the coolant has reached it's operating temp, before the oil then catches up to it. I can estimate approximately when the oil has reached operating temperature in my Firebird though, based on the oil pressure gauge (it'll show 18psi at idle or 40psi at 60mph when the oil is up to temp) But the Honda doesn't have an oil pressure gauge at all.

 

[Patman]

quote:

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Originally posted by TooSlick: Chris, I have factory installed oil temp and oil pressure gauges in my Audi 100 sedan. When the temps are below freezing it takes 10-12 miles for the oil to come to an equilibrium temp of about 190F. I'd say any trip less than ten miles clearly falls into the severe service catagory, particularly in the winter. You will get more fuel dilution, moisture and general oil contamination under these conditions. Some of these newer hypereutectic (sic) aluminum pistons are quite loose in the cylinders when the engine is cold, hence the piston slap you see discussed. This also means you are getting more "blowby" while the engine is warming up.

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Yep, in my last UOA for the Firebird, which was entirely winter driving, I saw 1% fuel in my results, while in the previous reports (which were all in summer weather) I saw no fuel at all. In my wife's Honda, and my sister's Honda too, both of their UOAs showed 0% fuel, even though they drove in the same weather. So their engines quicker warmup time (and lower mileage engines) helped them out.