james280

I’ve been hearing for years that lots of short trips are not good for your car – ideally, you want the car to reach normal operating temperature with every use.

My 2016 Targa (25k miles) is my daily driver and while we also have two SUVs in the family, we also have two other drivers, so I’m forced at times to use the 911 on short trips around town (oh… poor me). I always keep revs low until its warmed up.

There’s a lot of technical expertise on this board – what are the impacts of regular, unavoidable short trips where the engine temp doesn’t reach full temperature? Often water temp will get there, but not oil temp which takes a lot longer.

asellus

The tl;dr here is that you're dumping soot and water into the oil, as the cold engine is extremely inefficient and cold start enrichment trims exist to make it run super rich to heat up the catalytic converters and idle higher for faster warmup and higher oil pressure.


To get just a little bit technical though --
The soot in the oil is what makes it black. This isn't avoidable, but short trips increase the percentage of time that the engine is running in a state that deposits a lot more crap into your oil substantially. The detergents in the oil will take care of this for the most part and regular oil change intervals complying with the time and mileage limitations outlined in your owner's manual will alleviate any and all concerns here.

The water in the oil is the real problem. It's not necessarily all in the oil either, steam in the crank case condenses on the (relatively) cold surfaces. This causes surface rust on components, usually bearing surfaces, in the crankcase that get scraped off when you next start the car and is taken care of by your oil. We're talking miniscule, barely-measurable amounts of wear here, but the wear is there and it does add up -- just not in any way that you as the owner of a 25k mile 2016 will ever see any negative impact from. We're talking reducing engine life from 200k miles to 185k miles, to pull some random numbers out.

All the water is steamed (or boiled) out of the oil and crankcase, sucked through your intake, and burned through the engine when you bring it up to temp and drive for a bit. A good 20 minute drive at OT on the freeway is enough to do this, and so long as you do that once every week or two on a car that is truly driven daily, you have absolutely nothing to worry about.

Ironman88

Reduction of viscosity in your oil (shear) - resulting in less protection against friction within the engine and creating a condition for increased engine wear.

Consequently one would need to address this with more frequent oil changes.

james280

I appreciate the responses... I make it a point to regularly get out there and drive at highway speeds and, of course, regularly change the oil, but I'll step all that up if I'm having to do a lot of short trips.

desmotesta

I frequently take short trips especially in this new post-covid era. Although short drives come with all of the above mentioned cautionary drawbacks, the most important thing to remember is the oil/coolant temp. I never Rev past 3000 until coolant is at full operating temp and oil is at least 150F. until then, I drive it at or under 2500 rpm (making sure to also never "lug" the engine in a tall gear and very low rpm)

During some of my short drives, the engine oil barely comes up to full operating temp. I have also been a huge proponent of not idling the car at lights, in parking lots or while waiting even in drive throughs. all of this adds up. But at the end of the day, its a car that I love to drive and just BE in, even if I am not driving aggressively, so i am going to enjoy it every chance I get.

Ironman88

Oil temp is the true indicator. The coolant temp gauge is not.

Pb Pedis

If I'm going anywhere in it, I let the car warm up to full operating temp (both oil and coolant) before starting the drive no matter how long or how short a trip it will be. It's not a daily driver so each ride is a special occasion I plan in advance without the need to hurry and get going quickly.

james280

I believe you're saying that you start the car and let it sit to warm up. Pretty sure you're going to hear from people on this board that's not a good idea - you should warm up the engine by driving it.

asellus

Well...

This.

Idling a car to OT is a relatively terrible thing to do. It's wasteful and damaging. You should start driving as soon as you have a few seconds of oil pressure so everything's circulated -- this takes up to about 30 seconds in the dead of winter, and is almost immediate in summer.

The reason here is you're spending more time in cold start enrichment (so more soot from the rich burn) at a low rpm (lower oil pressure).

Will it murder the car? No. Will it have a significant impact on the longevity of the engine? Yes, but probably not during your ownership.

Levy

lots of good info/advise in this thread. just chiming in to confirm what's already been said. not going into the "why's" because they've already been described very well in above posts.

worked for Honda Mfg for almost a decade in Marysville Ohio. spent about a year at the Anna Engine Plant where i interacted with many engineers. guys who have spent decades designing and building engines for Honda. more importantly, they spent just as much time testing engines designs for wear and other issues. several of these guys had F1 experience with Honda in the 1980's and early 90's. they know a thing or two about engine's and how they wear. they have decades of *intense* research/analysis to back them up.

Don't idle your car until it's warm. drive it mellow until it's warmed up instead......FACT/True
Don't drive hard/at higher rpm's until you are near or at normal operating temps...FACT/True
Short trips without reaching operating temps are not good for your car...FACT/true
Occasional high rpm driving is a good thing, especially if you don't like to/seldom do it driving normally...FACT/True

violating any of the above will not cause your car to immediately self destruct =). just good common practice if you want to extend the life of your drivetrain

Carreralicious

In a related question, how about after the engine is fully warmed up?…will idling a long time also damage the engine? I ask cause in the winter, when taking the car to a self serve wash, sometimes the line is long and you have to sit idle for a long time before it’s your turn to wash the salt off the car, and too cold to just turn off the engine.

raaizin

I would just change the oil every 5k and never let it go past a year in time if you dont hit the 5k miles. You could also have issues with your exhaust if it doesnt get up to temperature as water from condensation may attack some of the metal from within. I really wouldnt lose sleep over this.

rileyracing1

All of this is great information just don't do the negative stuff too often if it can be avoided ...after all it's a damn car and don't worry about it too much we all get stuck in traffic and have to idle for ten min now and then and as mentioned change your oil every 5k or once a year or sooner and live your life guilt and worry free we all could get brain aneurisms tomorrow and croak...

Jack F

Lead Foot, start the car, turn on your favorite tunes and go. Don’t idle.

Pb Pedis

This is why I read these forums. I honestly did not know that warming it up before a drive was a bad idea. Thanks guys!