Is push to change fluids just a scam?

By Doug McAllister

Q. To follow up on your recent column (about transmission fluid changes), at the dealership where I have my car serviced sometimes, they are telling me I need a power steering system fluid flush and replacement of fluid.

I don't think this is an inexpensive service repair. I have a 2006 Ford Mustang GT with about 75,000 miles on the car. I was going to go ahead and get it done, but then another mechanic is telling me not to.

He says it is a dealership come-on just to make money and tells me it is not necessary. Now, I don't know what to do.

Also, you may have talked about this in a previous column, but what is the general rule of when (how often) to get radiator coolant flushed and changed in a 9- to 10-year-old car? I believe I have had one flush and change of coolant fluid about four years ago. The fluid itself is about $30 per gallon (Motorcraft Gold) and not standard Prestone or store-bought fluid

Thanks for your great column!

A. Thanks for a great question. I do recommend that you change the power steering fluid on a regular basis. However, it is a much longer mileage interval than other fluids, probably 50,000 to 60,000 miles.

In the past, most of our cars had steering boxes, which are sometimes referred to as a steering gear. For the most part they kept the fluid fairly clean. Almost all cars today have some type of a rack-and-pinion steering mechanism. The way they work, moving back and forth, creates wearing of the seals and other components. As this wear occurs, it leaves deposits and contaminates the fluid over time.

Once the steering fluid becomes excessively contaminated, it can start to cause additional wear. Some manufacturers recommend a change at certain intervals, but not often over the life of the vehicle. It is not that expensive of a service in most cases and, again, it is not one you have to perform frequently.

With regard to engine coolant, it depends on the type of coolant you are using. You can extend the interval with the higher-quality coolants, like you mentioned here.

I think four years is probably too long, though. Again, the manufacturers have caused us to think we don't have to service our cars anymore but that's just not so. Over time, engine coolant begins to turn acidic. When it does, it can begin to corrode engine components like the radiator, for example.

So once again, regular coolant maintenance can save you a bigger expense and inconvenience down the road. I think between two and three years is a good rule of thumb. However, this might vary a bit based on climate, driving habits and the age of the car. Check your owner's manual to see what the recommendation is and adjust from there.

As always, it is best to find a shop you trust and then trust their recommendations!

• Douglas Automotive is at 417 W. Main St., Barrington, (847) 381-0454, and 123 Virginia Road, Crystal Lake, (815) 356-0440. For information, visit douglasautomotive.com. Send questions to underthehood@dailyherald.com.