Many cars have been sold with the vehicle manufacturer touting “lifetime” fluids, which means certain fluids never need to be changed during the lifetime of the vehicle. This sales technique was implemented to help relieve the fear and intimidation some consumers were experiencing if thinking of buying a European vehicle. Now, Asian and domestic manufacturers are following suit.
Let’s begin with engine oil. Now, to date, I don’t know of a manufacturer that has been so bold to claim the engine oil never needs changing. However, manufacturer-recommended oil change intervals have been slowly increasing, with some intervals now at 15,000 miles. Many newer cars don’t have oil dipsticks, but instead use a display within the instrument cluster to show the remaining life of engine oil. A computer then calculates oil life based on fuel consumption, among other things, as fuel contamination is the primary cause of oil break-down.
We recommend replacement of the engine oil every 3000 miles for an older, high-mileage car. Every 5-7k miles is a great interval for cars requiring synthetic oil. Replacement costs of factory-built engines are now approaching $10,000, or more. It’s better to be safe than sorry.
Moving on, automatic transmission fluid or ATF, has also been designated as a lifetime fluid by some vehicle manufacturers. ATF is SW-30 oil loaded with detergents to keep the inside of the transmission virtually spotless. The oil is filtered by means of an ATF filter before it is pumped throughout the fluid circuits, which allows the transmission to shift gears. Once the fluid breaks down, or the filter becomes clogged with materials, the transmission stops working properly.
With newer transmissions having 9 or 10 speeds, the cost of replacement is nearing $10,000 for some units. Paying a few hundred bucks every couple of years for maintenance doesn’t sound so bad, eh?
Brake fluid. It is a hygroscopic fluid. This means it readily absorbs water, right through the plastic container! The primary function is to transfer and multiply force from your foot to the brakes at each wheel on your vehicle. It also holds heat. By means of fluid dynamics, 8 lbs. of force from your foot multiplies to over 400 lbs. at the caliper! This multiplication is dependent on the fluid being noncompressible. When contaminated with moisture, which happens naturally over time, brake fluid loses its ability to transfer force and hold heat. This translates to a spongy brake pedal. Worse yet, the boiling point of brake fluid is reduced about 60 degrees for every one percent moisture content. Standard brake fluid boils at 284 degrees F. This means at three-percent moisture content the vehicle is simply unsafe.
We’ve had many people contest the above information. Of course we’ve been accused of selling a fluid service for a fluid that appears clean. Do we wait until our engine oil is black before we change it? Nope. There is no greater basis for recommended fluid maintenance than what we’ve experienced in the shop.
In summary, cars, when maintained properly, are very durable. This maintenance includes, above everything else, fluids. Have your trusted local repair facility, with their ASE-certified technicians, change your oil and fluids. The professional shop will be using factory specified oils and fluids, and will help spot early signs of trouble if they exist.