In my last post, “Don’t Forget About the Trailer“, I talked about a customer of ours whose fifth wheel trailer was in serious need of attention, and ended it by promising to touch on his tow rig in the next post. As it turns out, the tow rig needed almost as much help as the tow rig, but the owner didn’t know it.

An otherwise well-maintained truck, we started asking him about the maintenance schedule and found that the power steering fluid had not been flushed in 100,000 miles. From the outset, that might not seem like a big deal, but the power steering is subjected to a lot of heat and stress. Factory recommendations may vary, but we recommend that the power steering fluid be changed every 3-5 years, or 50,000 miles. Power steering pumps in heavy duty applications like this customer’s F-350 4×4 are under more stress than in passenger cars, because they are moving more weight. And, bigger tires common on 4×4 applications create even more resistance.

If you don’t flush the power steering system, the oil becomes contaminated with dirt that can cause seal and pump wear. And power steering systems don’t have filters, either. There are filters available, but be very careful that the filter you’re considering doesn’t cause a restriction. I remember some people were putting in-line transmission filters on their automatic transmissions, and subsequently frying them because there wasn’t enough oil flow.

We ended up flushing his power steering system and adding a product called LubeGard Power Steering Fluid Protectant to the power steering fluid. This product uses rapeseed oil, a replacement for the Sperm Whale oil they used to use in these systems and automatic transmissions back in the ‘70s and ‘80’s. Rapeseed has better lubricity and cuts down on pump wear. We also added LubeGard Automatic Transmission Fluid Protectant to the transmission as well.

One thing lead to another, and we found out that the brake fluid had never been flushed, either. This is another thing that a lot of people don’t think about, but brake fluid is hydroscopic, in other words, it attracts water. When too much water gets in the system, it lowers the boiling point of the fluid and can cause brake fade. Plus, the water causes corrosion, and it was already starting to happen in this truck. Though the owner didn’t know it, the right front caliper had begun to stick due to corrosion, and the inner brake pad was wearing prematurely.

We flushed his system with DOT 4 brake fluid, which has a higher boiling point than the recommended DOT 3. Some people like DOT 5 silicone brake fluid because it has a very high boiling point, but we don’t use it for a number of reasons. Silicone fluid is not hydroscopic, so instead of water mixing with it, it collects in one area of the brake system and will not dissipate evenly. Plus, it can’t be mixed with ethylene glycol or polyethylene glycol-based brake fluids; the entire system has to be very carefully flushed first. For customers that want a brake fluid with an extremely high boiling point, we recommend DOT 5.1 non-silicone brake fluid. Motul makes an excellent DOT 5.1 non silicone fluid that has a dry (out of the can) boiling point of 522 degrees F, 365 degrees F “wet”, or when in mixed with some water in a braking system.

Typically, we recommend that a brake system be flushed every two-three years, regardless of mileage. If you live in a damper climate, you should change the fluid more often. One easy way to check the condition of your brake fluid is with FASCAR Strip Dip test strips from Phoenix Systems. FASCAR stands for “Fluid Analysis by Stimulation of Contamination Alpha Reactions.” You simply dip the strip into the vehicle’s brake fluid for one second, and within two minutes, the “reaction zone” will change colors depending on the condition of the brake fluid. This product is relevant because it measures the “virtual age” of the fluid. As the company’s literature explains, a vehicle may only have 12,000 miles on it, but due to the thermal effects on the brake fluid, it may have the a ‘virtual age’ of brake fluid with 30,000 or more miles on it.

We turned the customer’s rotors on our Pro-Cut on-the-vehicle rotor lathe. I think turning the rotors on the vehicle is a much more accurate method, as the rotor is being turned on the axle it runs on, which eliminates “stacked tolerances” and run out problems. A lot of people don’t realize that if you take a rotor off for any reason, it should go back the same way, on the same studs. Always mark the stud, and mark the rotor where it came off in order to avoid run out problems and vibration.

Everyone knows a vehicle requires maintenance, and most of us know that items like engine oil, coolant and transmission fluid require frequent checks to ensure long life. But remember there are other systems in your tow vehicle that require maintenance as well, and should be serviced regularly to not only for durability, but safety as well.

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  1. I found this article very interesting and informative so I made a copy to show my husband and our mechanic. We have a 2004 Ford F-250 V-10 which we bought 2nd hand from a dealer. The dealer will have all the records so I can show this to the shop forman and have him check the history of the truck. We haul a 2002 Sunnybrook fiver and are heading west this fall. Now we know what to have checked besides the usual. Thanks! Lou Giddings

  2. Hello Bill,
    A lot of the newer pick ups use a sealed cartridge bearing that you do not repack. The rotor slides off the studs allowing you to put it back on in another location. That is what I mean by indexing or marking the the rotor to the stud.
    Sorry about the confusion.
    Have a great day, Robert

  3. Bill Miller

    Hello Rob’t Henderson, Regarding your comment about front brake rotors, what do you mean about marking studs ? They only mount one way and you normally mark them right or left for their respective sides. You’ve lost me on this one . Thanks, Bill Miller