When I was a kid, my dad would have to take the car down to the garage every few months for a chassis lubrication, usually at the same time as the oil and filter change. Now, apart from a few components, the chassis lube is now a thing of the past.

That kind of progress has been making its way to fluids, which are now commonly labeled as lasting for a “lifetime.”

What does lifetime fill mean?

The words “lifetime fill” raise a few questions, including whose lifetime — mine or my car’s? It’s a good question and one reason to read the fine print from your vehicle’s manufacturer. Lifetime fill doesn’t mean the fluid will last for 80 years. “Lifetime” refers to one of two things: what the manufacturer expects to be the average usable life of the vehicle or the life of your vehicle’s warranty. The exact definition of “lifetime” varies by manufacturer, but one thing they all have in common is that the fluids have a lower viscosity (i.e., they’re thinner). And they are designed to resist breaking down chemically as early as standard fluids do.

Common lifetime fill fluids

While these long-lasting fluids vary by manufacturer, the most common ones are:

• Rear differential fluid

• Transmission fluid

• Brake fluid

• Coolant

Unlike the systems that replaced regular chassis lubrication, these aren’t always sealed. Depending on the manufacturer, you can usually refill or replace these fluids. But if your vehicle’s manufacturer says they’re lifetime fill, it means that you shouldn’t need to under normal operating conditions. If you operate your car under what the manufacturer considers “severe” conditions (whether you consider them “severe” or not), that lifetime fluid might require changes at very specific intervals. (See Vol. 39 #01 of The Loop newspaper: “Severe vs. normal driving conditions”. Available online at http://www.theloopnewspaper.com.)

For example, some manufacturers that offer lifetime rear differential fluids consider driving on dusty roads to be severe conditions. So, if you keep your 4×4 on pavement year-round, your fluid is good for a “lifetime.” But if you spend time off-roading or traveling on dirt roads, you may need to change your fluid regularly and on a schedule. If you use your vehicle to tow a trailer, your “lifetime” transmission fluid, brake fluid and coolant might not last as long. Again, check your owner’s manual and read the fine print.

The pros and cons of lifetime fill

The upside to using lifetime fluids is that you’ll have to do less maintenance over the life of the vehicle (or your ownership of it). The downside? If you start to get complacent about the fluids that do need replacement, such as engine oil, you’ll end up regretting it.

If you are particular about keeping your car in tip-top shape, consider replacing lifetime fluids occasionally — a periodic checkup on your car’s inner workings is not unlike bloodwork and other tests your doctor orders before your annual physical.

And if you’re a typical driver, lifetime fluid fills may give you peace of mind and one less thing to worry about.

For more information on lifetime fluids and other common car questions, chat with a knowledgeable expert at Protech Auto Service, located at 410 West J St., #G, Tehachapi. They can be reached at (661) 822-1100.