• Apr 19, 2006

The Car Connection's resident mechanic, Doug Flint, wants you to resist the next time a quick lube shop tells you that you need your transmission fluid/differential oil/transfer case fluid/etc. etc., changed. Resist their scientific-looking pH strips and the repair guy's claims that the [insert fluid name here] fluid is just a little too [insert color here].

Doug Flint, in his infinite mechanic's wisdom, finally tells us what we've all been longing to hear ,but were too afraid to believe -- the only thing those repair shops are flushing is your wallet.

Read on for his advice on fluid exchange intervals and advice on resisting even the hardest of extra service sells.

[Source: TheCarConnection.com]



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    • 1 Second Ago
  • 12 Comments
      • 8 Years Ago
      Well Doug, I think you're wrong, it's not being oversold, it's being overbought. You can try selling anything, however, until the money changes hands, nothing happens.

      Regarding your "sealed" theory on brake fluid. Brake fluid has a very high affinity for moisture and the "seal" can be pretty easily lose it's integrity, every couple of years is not a bad idea. Even in the "good old days" of not changing it until brake work is done, I hate to tell you how many pitted wheel cylinders and calipers I used to see caused by corrosion. I think I'd rather flush some fluid than replace wheel cylinders or calipers.

      I'd agree on his take of flushing/changing the other fluids about every 30,000. As to coolant, hey every 2 years, just ask some owners that had the 100,000 mile stuff about clogged heater cores.

      It's always sort of made me laugh as to why someone is so worried about what I may pay out of my pocket or others might. Good press I guess.

      • 8 Years Ago
      I don't track maintenance visits in my reliability research at http://www.truedelta.com for two reasons:

      1. It would require a lot more work from participants, and I want to keep things as easy as possible

      2. Every dealer/shop I've ever visited recommends far more work than the manufacturer's maintenance schedule calls for

      As result of #2, maintenance costs are driven more by how much the owner believes the dealer than the car itself.

      Oddly, fluids have been around for decades, but when's the last time anyone presented the results of a scientific study of the impact of frequent fluid changes? I've never seen one.

      What I might do once I have a good amount of repair data is have people indicate which maintenance schedule they tend to follow, owner's manual or dealer's, and see if this predicts anything.
      • 8 Years Ago
      "You are probably one of those guys who is whining about his leaking intake gasket on his 6 year old car with 150000 miles and still sporting it's original coolant!"

      Actually the newest vehicle I own is a 1989 with 251,000 miles on it. It runs like a top. The combined age of my three vehicles is 91 years. I do all of the maintenance and repairs on my cars (in the very rare event a repair is needed). And they never go anywhere near a dealership.

      I never said fluids don't need to be changed. They indeed do, but follow the manufacturers recomendations. Do not follow the recomendations of someone trying to sell you a service.

      Yes I do know that brake fluid absorbs water. I have done a great deal of brake repair in my day and that is perhaps the one area where I would differ with Mr Flint. It should be flushed periodically. Again follow the manufacturers recomendation.


      When you suggested there is not a difference between engine oil and the other fluids you demonstrated that you either don't know what you are talking about or you are dishonest. Which one is it?
      • 8 Years Ago
      I think this guy needs to get his head out of the sand. What makes differential fluid, tranny fluid, or coolant any different than engine oil? All of these fluids are subject to heat and stress. I can't understand why people refuse to maintain their $30000+ vehicles. I work at a dealership and it makes me laugh how someone will spend a grand to fix their AC but "leave the brakes until next time". Brake fluid does break down over time-with wheel cylinders and abs controllers becoming the victims. Overheat your transmission fluid and you'll cut it's lifespan in half. The "oil change only" crowd are the ones who trade their vehicles in and require 2 grand worth of work to make them safe for the road.
      • 8 Years Ago
      I've never used a flush machine to change my trannie fluid. The same result can usually be achieved by removing the supply line running to the radiator and letting it be pumped out.
      • 8 Years Ago
      The other thing is, you should change all the lightbulbs in your house at least once a year, even if they *seem* to be working fine. Got a problem with that? Hey, buddy, your house is worth $300K. You're gonna tell me you're too cheap to swap out your lightbulbs???!!!

      (Kudos to Doug Flint. I have a feeling he's now a marked man in his business.)
      • 8 Years Ago
      Common sense tells you fluids must be changed to increase the likely hood of a more trouble free ownership.
      One lister said he could'nt understand why people don't want to maintain their $30,000+ cars. The answer is simple; car prostitution, otherwise known as leasing. If you aren't a person who keeps a car for an extended period of time I guess it's hard to disagree with not taking care of your car.
      If you own your car you will pay either way, be it maintance or repair. It's a personal preference. I perfer to pay for maintance. That way I deside the time the car goes into the shop and will hopefully avoid surprises.
      • 8 Years Ago
      Look, if a particular service or flush were necessary it would be in the owner's manual; am I right? Am I wrong? No. Every recommended service is that much more potential money in a dealer's pocket, so to reward their dealers the manufacturer is darn well going to recommend that service if it's truly required. Why in heaven's name would anyone change the oil more frequently than required in an engine that sees only normal usage. The manual says 7500, but you know better? I'm all for being conscientious, careful, and conservative with vehicle maintenance, but keep this in mind, every time a mech UNNECESSARILY touches your vehicle you run the risk of his inadvertently doing something to damage the vehicle: cross-threading a bolt, forgetting to tighten a line, etc. Here's the bottom line: other than for recommended routine maintanance, if it ain't broke, don't fix it.
      • 8 Years Ago
      #7
      "What makes differential fluid, tranny fluid, or coolant any different than engine oil? All of these fluids are subject to heat and stress."

      What is the difference?
      Engine oil gets contaminated by combustion by products. That is the reason engine oil must be changed much more often than the other fluids which are not exposed to combustion gasses.
      Did you really not know that? I think you do but as you said, "I work at a dealership".
      • 8 Years Ago
      Richard, or should we call you.....

      Why is it that there is always someone like you that just has to post crap like this. It's the "I know better" syndrome.

      So informing the public to watch out for a common scam makes you laugh? I believe that says a ton about you. No I don't fall for this crap personally, but I'd love to send it to my mother and father in law whom often believe anything a mechanic tell them. The more you inform the public the better educated they become.

      But that is all common sense, you were just being the typical troll.
      • 8 Years Ago
      I don't know about you guys, but I've never had a transmission go bad from changing the oil too often. I'd rather be a little conservative when changing fluids than pay the price down the road. Of course it's not as big of a deal if you do it yourself (BMW dealership quoted me $200 to change transmission & final drive oils, I did it myself in an hour for about $30 in fluids).
      • 8 Years Ago
      Good news bad news department. The bad news, is that lube shops are not using factory fluids for replacement. In the case of Chrysler automatic transmission fluids, this is almost always a recipe for bad transmission shifts and eventual transmission failure. But the truth is, almost every maker has VERY specific fluid replacement specifications (except, oddly enough, brake fluid) and its wise to use the factory fluids. Certainly NOT using them, puts your warranty at risk. Most manufacturers won't license third parties to sell their fluids, so third party products, even though claiming to be compatible or satisfy factory spec, are reverse-engineered and not licensed - designed to perform like factory, but not factory formulation.

      The very good news, is that with the proliferation of lube shops with equipment and a basic level of mechanical skill, it is possible (i) to get fluids changed while you wait; (ii) to watch and make sure it gets done; and, best of all (iii) to carry in factory fluid. The RIGHT factory fluid.* And it's cheaper, too.

      *I am dismayed not only by factory dealers that use 10-30 oil for oil changes, when 5-30 is specified; but also by, for example, Dodge dealers who don't stock the expensive ATF +4 fully synthetic fluid, and use the lower grade ATF +3 factory fluid for changes on the more recent vehicles that call for +4. Can dealers mess up like this too? Unfortunately, yes. The same people who oversell you routine maintenance sometimes don't even read their own manuals or follow their own specs. How about replacing long life coolant with short life coolant? That happens too.