Should 4WD be engaged regularly to keep it in good working order?

Dear Car Talk

Dear Car Talk | Dec 01, 2001

Dear Tom and Ray:

Is it wise to occasionally activate a four-wheel-drive system to keep it in good working order? My mechanic advises I do this for a short distance. -- John

RAY: Well, as my elderly Jewish grandmother would say, "It vuldn't hurt."

TOM: We have an elderly Jewish grandmother?

RAY: Well, no. Not really. That was just artistic license.

TOM: Most of your 4WD systems will be fine for a long, long time without ever being used. The gears, for instance, are all submerged in oil, so nothing's going to happen to them. And the locking hubs should be covered with grease, so they shouldn't rust or freeze up, either.

RAY: But there are some switches and solenoids that could get sticky and fail if they're left long enough. So, once every few months or so, it's fine to put the vehicle in 4WD and drive it a short distance.

TOM: And by a short distance, we mean you can drive it down your driveway and back. There's no need to drive the truck from here to East Armpit in 4WD just to make sure the switches work.

RAY: And besides, it's dangerous to operate traditional ("on demand") 4WD on dry pavement. It can cause unpredictable and dangerous handling. It can even cause the vehicle to flip over if you have to swerve. Old-style 4WD is ONLY supposed to be used in snow, mud, sand or off-road -- conditions that allow the wheels to slip and "unbind" themselves.

TOM: So yes, John. Drive it a short distance once or twice a year if you don't end up using it normally in slippery conditions. But make it a very short distance. And don't forget to take it out of 4WD before you head back out on the road.

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