What Are Fill For Life Fluids?

Car shoppers are getting savvier by the minute and considering long-term costs in their new vehicle purchase decisions more than ever.

For reasons like this, many automakers have abandoned the dreaded timing belt in their engines. Why? A timing belt is a cheap part that requires a preemptive change at a preset interval. Although the part itself is cheap, the labor cost to replace it, perhaps every 60,000 miles, can approach $1,000 or more on some models. As a result, many shoppers actively avoid buying a timing-belt equipped vehicle, meaning today, timing belts are rarer than ever as the maintenance-free timing chain takes over.

Offering shoppers lower ongoing running costs helps sell cars. That’s one of several reasons that more models these days are using so-called “lifetime fill” or “fill for life” fluids, which, in theory, never need to be replaced for the life of the vehicle. If you’re one of the many shoppers considering maintenance costs in your purchase decision, avoiding certain fluid changes can add appeal and save you hundreds of dollars or more.

“Over the years, oil and fluids have offered improved formulations that are getting better and better,” says Daniel Grenier, a Dealer Technical Support Manager with Mazda. “Therefore, it allows the manufacturer to change the scheduled maintenance. Cost of ownership and environmental benefits are also a factor.”

Still, there are a few things you should know about lifetime fill fluids, especially the fact that in some situations, they don’t actually last the life of the vehicle.

Even lifetime fill fluids may require a fluid change if the vehicle is driven in what some manufacturers refer to as severe conditions. These may include frequent driving on dusty or dirt roads, frequent driving in stop-and-go traffic, towing and hauling, or frequent driving in extreme cold.

That means many drivers in many locales should follow the severe service schedule for fluid changes, which may require lifetime fill fluids to be swapped out and replaced on occasion.

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In simple terms, fill for life fluids are not, in fact, filled for life, but every manufacturer is different.

For instance, the Mazda CX-5 requires no fluid change for the rear differential, unless it’s been submerged in water, or if the vehicle has been used to tow a trailer, driven in sandy, dusty or wet conditions, or driven on repeated short trips. Translation? If you drive your CX-5 in nice weather, solely on longer trips on clean roads, the rear differential fluid never needs changing. If you tow a trailer to your cottage, down a dusty road, and spend any time in stop-and-go traffic, you’ll need to change the rear differential fluid periodically.

But in regards to the transmission, the CX-5 has no service schedule for a fluid change, severe use or not. Engine coolant is not filled for life but in the CX-5, it doesn’t need to be changed for 10 years or 120,000 miles. Again, remember that the fluid change intervals and conditions that void the filled for life fluid premise vary from automaker to automaker.

Note that some manufacturers have condition-specific fluid changes specified for brake fluid and power steering fluid, too. Also, it’s worth mentioning that engine oil is never a fill for life fluid and that skipping or prolonging oil changes is a very bad idea that will likely ruin your engine and void its warranty.

On a personal note, immediately after my mother bought a new-to-her 2012 Hyundai Elantra (which boasts fill for life coolant and transmission fluids), I had her visit her mechanic to change those fluids out. Overkill? Maybe but the total cost was under $100 and the peace of mind that comes from knowing the vehicle is running fresh, quality fluids is more than worth it for us.

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Many savvy vehicle owners interested in long-term durability and trouble-free operation from their rides choose to change all fluids on a regular basis — lifetime fill, severe use or otherwise. Like many drivers, I’m a fluid-change fanatic and adhere to the principle that you can’t overchange fluids and that doing so is cheap protection against potential problems down the line.

It’s a choice that many mechanics agree with.

Grenier says that cautious owners who wish to change their fluids more frequently than required have nothing to worry about. “There is nothing wrong with replacing the fluids regularly, as long as the recommended fluids are used. It will not void Mazda’s warranty if the proper fluids are used.”

“Changing your fluids is cheap insurance,” said Paul Kennaley, another automotive service technician. “In my own vehicles, I change fluids regularly, ahead of schedule, and whether or not a fluid change is required as per the owner’s manual. Is it overkill? Maybe — but I see enough problems in the course of my work week caused by deteriorated fluids and poor maintenance, and to me, the small cost of a fluid change provides great peace of mind.”

Car shoppers should remember that on-time fluid changes are vital to maintaining your remaining powertrain warranty in good standing. Seek service records when buying a second-hand car that’ still under warranty to make sure that all applicable fluid changes are up to date. If you can’t confirm a replaceable fluid was last changed, be sure to budget to have the work carried out. In some cases, a warranty claim could be denied if the vehicle owner doesn’t change a lifetime fill fluid, but lives in an area where the severe service schedule applies. This would typically be up to the discretion of the dealer and drivers should always stick to the severe service fluid change schedule if in doubt.

Finally, don’t forget the less popular fluids. Many vehicles have fluids in their differential, transfer case, steering system and even braking system that can be beneficial to change on a regular basis. Also, note that transmission fluid changes to models with a CVT or dual-clutch transmission should be carried out by a dealer, not a lube shop since the fluid itself and the procedure to change it is typically very specific.

Of course, like so many other aspects of vehicle maintenance, the answer on when, or if, to change certain fluids in your ride is an easy one: just check your owner’s manual.