Ever wonder how all-wheel-drive or 4-wheel-drive vehicles get the power from the engine to the front and rear wheels? The magic happens in what's called a transfer case.  In some all-wheel-drive vehicles, it's sometime called a power take-off unit, or PTU.

Inside the transfer case is a set of gears.  And to keep those gears meshing smoothly, they have to be lubricated and kept cool.  What does that is called transfer case fluid. Depending on your vehicle's type of transfer case, it is filled with either an automatic transmission fluid, a gear oil that's a bit thicker or transfer case fluid designed to be use for your transfer case.

As happens with all lubricating fluids, the transfer case fluid has things in it that break down the older they get.  They have corrosion inhibitors, detergents and anti-foaming agents that keep the lubricant from getting air bubbles in it. Transfer cases don't have filters in them to clean out impurities.

If you don't have your transfer case fluid exchanged for fresh, you risk damage to the case, and that can run into thousands of dollars.  So the wise driver makes sure the fluid is changed according to the manufacturer's recommendations.  For many vehicles, that is every 30,000 mi/50,000 km, but some require it more frequently.   Your vehicle service facility can advise you on what your vehicle's optimal interval is.

During the fluid exchange, any metal filings that may have come off are cleaned off of the drain and fill plugs that are usually magnetized to catch the stray metal pieces.

If you hear grinding noises coming from under your vehicle or if it is having trouble shifting gears or going in and out of 4-wheel-drive, those could be signs your transfer case needs service. In that case, have our technicians check it out.  The best plan of action?  Keep your transfer case fluid maintained and it should keep you heading down the road for years to come.

Car Fix Louisville
5411 New Cut Road
Louisville, KY 40214
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