By on April 21, 2016


car warranty. shutterstock user ibreakstock

TTAC commentator Arthur Dailey writes:


I take our two out-of-warranty vehicles to a local independent garage for maintenance. The owner is 100-percent honest and that is the most important thing. No unrequired work or surprises. He brings out all the replaced parts, the containers and bills for the replacements. He is not the least expensive, but he’s certainly less costly than any of the local dealers.

I have one vehicle, bought new, that’s had all work performed according to the manufacturer’s schedule. However, when I bring it in now, the conversation may go like this:

Me: “The book says that the coolant should be flushed and replaced.”
Mechanic (later that day): “I checked the coolant and it would be a waste to change it now.”


Our other vehicle is lightly driven and not regularly maintained. With that vehicle, the conversation may go like this:

Me: “I think we need to flush and replace the transmission fluid.”
Mechanic: “No. I don’t recommend that. That may stir up too much sludge and cause problems. I’ll just check it and add any if needed.”

As stated, I absolutely trust his honesty. However, while watching out for my pocketbook in the short-term, could this result in some long-term issues?

Sajeev answers:

A manufacturer’s service schedule likely has a metric ton of CYA car care for the uber-diverse driving habits its products experience, and the uber-expensive lawsuits that come with them!

Therefore, don’t change the coolant if the independent mechanic says it’s fine. He will happily earn your business when needed, as he’s earned your trust.

In this theoretical situation where I know nothing about your vehicles’ age/mileage/make/model, your local wrench would likely love to fix your car get paid, but is more interested in keeping you around. The last sentence drives the point home.

“while watching out for my pocketbook in the short-term, could this result in some long-term issues?”

Your local wrench says the same thing every time a customer (that can be convinced otherwise) wants over-aggressive fluid services for no good reason. He wonders what will happen if another wrench calls him out on his “fleecing,” convinces the owner they were duped, and then loses a customer for life. That same customer maybe, just maybe, is about to have a big-dollar item needing service (bent suspension from potholes, transmission rebuild, heater core replacement, etc) and that mechanic is gonna miss out on the payday.

You “absolutely trust his honesty,” therefore run with that. I do the same with my trusted local independent wrench: even when they get it wrong, they own up to it and fix it. You can’t ask for anything more, son!

[Image: Shutterstock user ibreakstock]

Send your queries to [email protected]com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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27 Comments on “Piston Slap: CYA Car Care?...”

  • avatar

    If you really wany to know. Get a fluid sample and send it to a lab.

    Draining the transmission fluid through the drain or by cracking the pan and refilling wont stir up any sludge and wont hurt it a bit. Depending on where your friction modifiers are. E.g. in the fluid like on a g.m. It can only help to replace the worn fluids.

    • 0 avatar
      Kyree S. Williams

      That’s what I did with my Golf SportWagen on its 20K-mile oil change. I was a little suspicious of VW’s 10K-mile oil changes on the TDIs. Even with my somewhat-spirited style of driving, the oil (although it did need to be changed) wasn’t detrimentally bad.

    • 0 avatar

      I agree. I changed the fluid/filter on my 220k-mile 1996 Aerostar (no longer owned), it resulted in smoother shifts, not failure. I drove the van another 10-15K miles before I sold it, no trans issues.

      I dont get the “its bad to change old trans fluid” mentality. Ive never had a trans fail following a proper service. Proper as in replacing the filter along with the fluid, and NOT a “flush” (unless its a car designed to be serviced that way). Ive seen failures immidiately following a “flush” without filter replacement. It was explained to me by a master tech, he said the flush will loosen and then trap all debris present in the filter, which restricts flow, causing failure. Makes sense to me.

      There is a reason my 215k mile Taurus still shifts great, it was regularly and properly maintained. Same with my parents Sable that they sold at 200k on its original transaxle. It had required a speed sensor at like 60k, but that was external and very cheap ($20), and thats all it ever asked for. Im fully aware of AXOD (and related) transaxle’s higher than normal failure rate, and I cant help but believe that proper service wouldve helped.

      As would have avoiding AAMCO. That speed sensor failure on the 1997 Sable at 60k? I took it to AAMCO first and was told it needed a full trans rebuild, and that I was “lucky” to have made it to 60k without it failing. I protested, and they said if I wanted further diagnosis, they would have to tear down the transaxle to find the exact issue. Im very happy I ran it by a Ford dealer for a second opinion, otherwise a $20 issue wouldve cost $2200+. Their goal is to get you to at least agree to a tear down, so they get paid for that, and you cant say “no rebuild” unless you want to pay them to reassemble it, which is probably 85% of the cost of a rebuild. Sharks. That isnt the only example I have of their awful business practices, but I think this post is long enough! Lol

  • avatar
    Compaq Deskpro

    Not changing the fluid is the best thing for him as it minimizes risk. It is not the best thing for you as it increases wear. Sure, you know that radiator is clean enough to eat off of and perfectly safe to flush, but he doesn’t, because he’s not your gearhead friend that you talk cars with, he’s a business man, and he only had to flush some 90’s Dodge minivan once and have it run great for a few days then implode for him to give the trans fluid speech to every customer. Strippers will treat you the same way. They will put on the girlfriend face and give you the girlfriend experience, but they are not your girlfriend, and sometimes this will show through. Don’t be shocked or offended, your mechanics not a bad person, but he needs to look out for himself just like you do. So just whip out the money, tell him you accept all risk for flushing the dirty fluids, and go on with your life, and leave him at the shop where he belongs.

    • 0 avatar

      Those early dodges did suck, but to be fair, never, ever let a fly by night place such as jiffy lube or amco do a transmission flush. Instead of using the proper oem fluid such as atf 4 or dex vi, they use a universal base fluid and an additive pack specific to the oem. It is complete fraudulent garbage and they should be sued out of existence for it.

  • avatar

    Coolant is fine to change on condition. It shouldn’t be dirty, should be able to pass a hygrometer test, and should be pH neutral.

    For the auto transmission fluid, it’s fine to drain, change the filter, and refill. Don’t just drain and refill as that dirty filter can contaminate the new fluid and it won’t work as well as a filter because it’s already begun to fill up. Remember, there is friction material in the clutch packs and that wears off. That’s why there is a filter.

    Do not get a auto transmission flush. Unless you want to buy a new transmission. That is per the transmission shop I used to frequent for work. In most cases, if a transmission had failed and needed to be replaced, they found that within the last 5,000 or 10,000 miles, the owner had the transmission flushed.

    That transmission shop also stated that if you note a burned smell in the transmission fluid, it’s too late to fix it. Time for a new transmission.

    • 0 avatar
      Carlson Fan

      Bam! Don’t use the word “flush”, tell him you want a “transmission service “. There is a difference. See above.

      And burned transmission fluid is why I love the fact that both my GM trucks have factory trans. temp gages. A must have for vehicles that are used for towing.

      The Volt, what transmission?….LOL

    • 0 avatar

      Not always true, I have replaced burned “yellow” transmission fluid in my old buick with brand new synthetic dex vi and it worked until i got rid of the car. I probably just got lucky.

  • avatar

    I say trust your indie, word of mouth is their key to business and since you trust him I am sure you say good things about him and that helps his business, my indie has saved me money, time and grief over the years and when I drop the cars off he knows what to do to keep them on the road and I have gotten him plenty of new customers over the years.

  • avatar

    Your mechanic can test your coolant, with either test strips or a hydrometer. Trust him.

    When it comes to transmission fluid, get it flushed every 60,000 miles, or don’t change the fluid at all and take the chance on replacing the transmission every 200,000 miles. Getting it flushed for the first time at 150,000 miles is a sure way to get it to fail.

  • avatar

    I obviously don’t know this mechanic, but personally, I would follow the maintenance schedule in the manual unless he was giving some sort of written guarantee on longevity.

    As far as “flushing” the trans, most manufacturers specifically caution against it and it is rare for me to hear a positive outcome from the procedure. Changing the filter and fluid seems to be the best way to service a trans.

  • avatar

    Just have him do a fluid/filter change, and install a drain plug for future drain/refill.

  • avatar

    What tends to wear out in auto transmissions is the friction lining on the clutches – it winds up as particles in the fluid. If your clutches are almost worn out, the only thing preventing your transmission from slipping while in gear may be the particles in the fluid – that is how the idea that flushing a transmission ruins it came about. Fresh fluid will have no particles. If your transmission is in good shape, changing/flushing the fluid will not hurt it. Therefore, it’s counterintuitive – if your transmission is old, and the fluid looks bad, flushing it may result in the need for replacement. If your transmission is relatively new, and the fluid looks good, flushing it may be a good thing.

    • 0 avatar

      In gm fluid, there are necessary friction modifiers are in the fluid to help prevent wear on the clutches. The fluid wears out wear out and then the transmission clutch plates start to wear, Ford is the opposite. Absolutely refresh worn gm fluid.

  • avatar

    I go through a somewhat similar experience with my mechanic, who happens to be my brother. I oftentimes have him go above and beyond, even when he advises against. Two weeks ago, we redid the lower balljoints on my 4Runner (’96, 128k miles). The truck drove fine and they showed no symptoms of wear, but as a peace of mind/safety component on this particular model (and 1st gen Tacomas, Tundras, Sequoias) it is highly advised to preemptively replace LBJs every 120-150k miles with fresh OEM units. My brother was opposed, but hey he was paid to do it. In the course of the repair, one of the likewise perfectly good factory outer tie rod ends was found to be quite stubbornly stuck in the old balljoint. We ended up sacrificing the tie rod end to get the balljoint out. Ended up having to temporarily install a made in China Advance Auto brand “Driveworks” tie rod which was the only way to get me back on the road in time. An OEM tie rod end is ready to be installed in its place. My brother definitely had a point in his ‘if it ain’t broke, don’t fix it” approach, but I really wanted the peace of mind of not having my wheel randomly fall off when I’m wheeling this thing out West next summer, in addition to adding some resale value to ‘those in the know’ who might be looking to buy this 4Runner from me in a few years.

  • avatar
    SCE to AUX

    I change transmission fluid every 25k miles. My cars no longer have a user-serviceable filter, but they do have a convenient drain plug (Kia), so it’s pretty easy to do.

    When I acquired my former 01 Elantra at 138k miles, I serviced its transmission (4-spd Jatco) on the same schedule. I don’t know if its fuid had ever been changed, but there it is never too late. That car had a spin-on transmission filter, which was awesome. It survived to 201k miles, when it succumbed to rust.

    • 0 avatar

      25K is a pretty aggressive timeline. I would have waited for 75K miles on our MkT if I purchased it new. Instead, I had it done at 50K miles and don’t plan on doing it until at least 125K miles.

      On my C-Max, transmission fluid change isn’t scheduled maintenance until 150K miles.

  • avatar

    I have an indie that I trust almost implicitly. However, and I have run into this with him as well, I still want to change the coolant based on MFG provided service intervals (or best practice), flush the brakes every couple years, exchange ATF, etc. Even if they don’t need it today, doing it today means I don’t have to think about it for another 6 years or 60K.

    Not too many years ago, I had a different well respected local mechanic fill my Mazda cooling system up with pure water, saying that since we are in Florida we don’t need to waste money on antifreeze. Needless to say, I never went back to that guy.

  • avatar

    It’s always a nice feeling when my mechanic refuses to take my money. And to go there and see the guy who’s owned it since 1977 – not working at the desk, but out there working on my old car.

  • avatar

    My indie shop will extract some coolant from the reservoir and run some kind of test on it. They’ll then tell me if it is still good or is ready to be replaced. So I go with what they say, regardless of the recommended change interval.

  • avatar

    About the usual density-based coolant testing: it does a great job of telling you whether the coolant will cool the car per manufacturer spec. However, it doesn’t tell you jack about whether the corrosion inhibitor package in the coolant is still functional.

    Change your coolant per manufacturer recommendation, or watch your heat transfer ability, and perchance your radiator, water pump seal, and other components, slowly fade away.

    Folks following the situation in Flint might understand.

  • avatar

    “A manufacturer’s service schedule likely has a metric ton of CYA car care for the uber-diverse driving habits its products experience, and the uber-expensive lawsuits that come with them!”

    Unless, of course, the recommended fluid changes fall within the free service period that some manufacturers include. In those cases all the fluids become ‘lifetime fill” except for engine oil, which supposedly lasts for 15K miles.

    Strangely enough, all these fluids are then recommended for frequent changes as soon as the free service period is over. Go figure.

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