JTS

Hi all - I have a question about "Auto 4WD" on my '99 Tahoe LT/4-door with the electronic transfer case. This is going to be my first winter with the Tahoe and I was reading up on 4WD in the manual. I understand when and how to use 4HI and 4LO, but I'm not sure about Auto 4WD. I don't have the manual with me now, but I recall reading that extended driving in 4WD isn't good for the drive train. I experimented with Auto 4WD in the pouring rain last night and I loved how the truck drove and handled on slick roads. Seeing as how I'm getting ready for 5 months of rain and snow, my question is: Is it safe to keep the truck in Auto 4WD? I assume that 4WD only kicks in when needed, so there shouldn't be a wear and tear problem right? How about fuel economy? As for 4HI, does the drive train warning in the manual mean that I can't drive for a few hours in a snowstorm in 4HI? Thanks for any info.

Tahoe

If you're going to be driving in severe conditions then leave it in 4Hi. If not, just have it in Auto4. Trucks like ours aren't designed to be run for hours at a time at higher speeds in 4hi.

when you're in 4wd in the snow, the second set of wheels only matter when you're taking off, or cornering...but as long as you take the corners slow, the Auto4 should be ok.

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dwestsr

According to the owners manual, you can run auto 4WD continuously. Only effect will be lower gas mileage. The 4wd hi and lo are a different matter. Only use them in slick conditions or off road.

BigA

It is a bad idea to drive around on DRY PAVEMENT in 4WD because there can be some binding in the drivetrain that will seriously wear out your components AND affect your gas mileage.

That being said, driving around in just rain or on just dirt roads isn't the greatest either - unless it is absolutely necessary. But it's not as hard on it as dry pavement.

If it is severe weather conditions like heavy rain, snow, ice, you should be able to drive around in 4WD as much as you care to - although I would consider looking into a tranny cooler.

As far as the AUTO 4WD - in my opinion, the term AUTO 4WD is a little misleading. As I understand it, when you have AUTO4 selected, the Transmission is shifted into 4WD, and the front drive-shaft is turning. The only difference is that the front differential only engages when it senses that you are slipping. So this, will still put a little extra wear and tear on your transmission and will still cut your gas mileage way down. As far as how well it works - how it responds to slipping, I don't know because I have never used it.

CalessaSSracer

If im up in the mountains in snow which would i use ?