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Fluids never changed but still are clean, hows that possible?

Hello folks,

I have 2006 Nissan Sentra that I bought pre-owned in 2010 with 70000 miles on it. Since this was my first car, I did maintenance what the mechanic told me to do, nothing more than that. It didn’t come with the manual and it never occured to me that I should google the manual. Yeah, stupid thing. I admit it.

Fast forward 2015, I got another car, this time brand new and it came with a load of literature. I went through the literature and figured how important that is. I searched for Nissan’s literature and found manual including factory service manual. Realized how I did not maintain the car.

Since then I am trying to do one by one maintenance. I was considering changing all fluids this summer. I checked brake fluid, transmission fluid, coolant. All have color that it is supposed to. Brake fluid is clear. Brake fluid valve are very well rusted (so doesn’t seem like ever bled). Transmission is red/pink in color. The coolant is green in color. Power steering fluid looks brownish.This confused me. I never changed the fluid or at least never paid for it. At a times, the mechanic did top up the fluids (as it was written on the invoice). Current reading on the odometer is ~103,000 I just don’t understand how these fluid look in good condition after driving for about 30,000 miles and 7 years.

Can anyone explain me? Still, I do plan to change all fluids but just can’t shake this thing and curious to know why.

Thanks in advance.

Your post is a little confusing… You still ahve the 06 Sentra, right? And some fluids still look clean? Brake fluid can look clean but absorbs water that reduces its effectiveness and corrodes the brake internal parts. Change it every 3 years or so. There are tools you can buy that check the water content in the brake fluid. Coolant - same but 5 years. Some say 3 years. The additive package that keeps things from corroding wears out and changing the coolant prevents corrosion in really hard to get spots. Oil - if it still looks reasonable clean on the dipstick right before an oil change - Congratulations! You are doing it right and your engine is Happy! Power steering fluid - if it doesn’t smell burnt and its still relatively clean, Great! But I’d still change it at about 80,000 miles especially if its brown… If in doubt, change it, its small money for peace of mind.

Hope that helps! The manual is the best guide but more often changes can help extend the life of your car.

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On which car? the 2006 or the 2015?

My apologies. Fluid changes are for 2006 Sentra. 2015 is being well taken care of since day 1. I just used that car as a reference.

You can’t always tell the condition of a fluid by its color. Change the fluids as per the manual, using only the proper replacements.


@ Mustangman,

Yes, I still have Sentra and all work is to be done on 2006 Sentra.

@ NYBo,
Thats exactly the point. I was expecting all these fluids to be rotten, at least brownish in color. From what I understood from YouTube videos that if ATF is not red/pink then it is due for replcement, other than the age of the fluid. Since I have NEVER EVER changed ATF fluid since I got the car, I am surprised to see that its pink. I was expecting it to be brown at least (due to the age of that fluid).
So the question is, if that ATF fluid is still in good condition or just like Mustangman said about the coolant and the brake fluid, just the color does not dictate the quality of the coolant and the brake fluid applies to ATF too?

I would change all fluids now with factory fluids, as others have said. Your car’s history may not have resulted in nasty fluids, but it’s definitely been enough time.

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2002 Sentra my daughter used to have was acquired at 82K miles, ATF was never replaced before I drained/refilled and the old one was in very decent shape: still red, no burnt smell and transmission was shifting OK, so I wonder if this small car simply does not stress it much. Brake fluid was “kinda ok”, but coolant was quite dark in color already. Prior owner did not do much (if any) maintenance.

Many, many cars are out there on the roads with over 100K miles, with no fluids ever changed except oil, and it hardly ever matters.

buying an old car, I would immediately walk away from the one with dirty fluids as it is a ticking bomb

mere 2 cents

It is amazing the cars that make it to 150k with nothing but oil changes.

I’d guess your ATF fluid was changed right before you bought the car. No mystery there.

I expect you already know that there’s a variety of different driving styles folks use. Just today on a 35 mph 6-lane city street the car in front of me displayed its brake lights a dozen times; while in the same distance (about 4 blocks) I only touched the brake pedal once, as I approached the stop light. All that go-stop-go-stop driving style accomplished nothing, we both ended up side by side waiting at the next stoplight.

I think the fact that the fluids look ok without keeping to the recommended maintenance intervals means your driving style is conducive to that result. And you may live in a mild, dry climate, which also helps. Engine oil and transmission oil are more likely to get dirty in appearance than the other ones too. One thing that’s certain, it seldom hurts and usually helps to keep your car out of the shop to follow the manufacturer’s maintenance schedule. So good for you – and your wallet – for getting your Nissan back on track.

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This was my thinking as soon as I read this. Who says the fluids were never changed? You got it used with quite a few miles so maybe the previous owner changed it. I came across a 1995 or 96 where the coolant had never been changed. The “coolant” now looked like black coffee and the reservoir was half full of rusty sludge. Does Nissan come with a long life coolant from the factory? It seems most cars are going that way which is probably good since many people never change their fluids.

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I live in NY, thats hardly a mild and dry weather, but my driving style is not aggresive at all. I am that fella on the road that looks young but drives slowly like the grandma.

Totally agree. That can very much a possibility that either the owner changed the fluids or the dealership did, but since the car came with no maintenance record of any kind, there is no way to know. Since I was a first-time buyer, I had absolutely no idea what one should look in the car. So I never checked these things until I got my Subaru.
Plus, the brake oil drain valves are totally rusted. That added to the suspicion.

Any used car is essentially a “black box” unless it includes all the service records - and from a dealer, they never do! Why gamble on what the previous owner did, or did not do? Any used car I buy gets all the fluids changed, period. That then starts the maintenance schedule and gets my preferred fluids - synthetic oils and DOT 4 brake fluid - into the car.

Brake fluid (not an oil, more like coolant) is probably the most ignored fluid on a car in the US. The Germans require the fluid pass a moisture test so manufacturers recommend changes every 2 years. Brake fluid quietly absorbs water over time. That water helps corrode the steel and aluminum in the brake system. That corrosion turns the brake fluid brown. Once you SEE it, some damage is already done. Rusty bleed (drain) valves would be the norm for a NY car that sees winter driving. It is just a problem to be dealt with in the rust belt.


I always change over to synthetic oils as well. One thing I notice is that the first change of synthetic gets dark a lot quicker. It seems that whatever crud is in the dark recesses of the engine gets dissolved because synthetic has superior cleaning properties as well. I usually go no longer than 3000 miles on the first change unless it looks like the engine was severely neglected and then I do 100-500 miles for the first change.

I have come across a few engines where the oil is very thick and looks like tar. Most are on mowers. Usually you know if the engine will hang together after changing to fresh oil pretty quickly. Some are so worn that the new thinner oil can’t cushion the excessively worn tolerances and they come flying apart within minutes. It is either that or some large deposit is broken loose by the detergents in the fresh oil which blocks something. Some actually hang together and then I give them another change,

I always give a used car a basic inspection myself. I get underneath and look for rust. Then I pull the oil cap and the dipstick. I look for sludgy deposits or mayo/milkiness in the oil or in the valve cover area. Sure, some things on just about any used car have likely been overlooked but if it is overall in pretty decent shape, you at least know the basics were taken care of. If the car looks like it was neglected and/or run hard, then either pass it up or try to get it so cheap that you will be able to take care of any problems that come up. Cars like this are a gamble.

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I think the mistake you’re making is that you’re assuming that if an automotive fluid doesn’t look dirty, it isn’t worn out or in need of being changed. If that is what you think, please consider this:

  • It’s a good idea to change your fluids before they wear out.
  • The oil on the dipstick will almost always look cleaner than the oil that drains out of the pan, because dirt settles at the bottom.
  • The only way to tell if a fluid (like motor oil) is worn out is to send it to a lab to have it tested, and that usually costs so much it’s just cheaper to change it than it is to have a lab analyze it.
  • If you wait until your fluids look dirty before you change them, you’ve already done some damage to the systems they’re designed to protect. The only exception to this rule is for motor oil in an old car. Motor oil in an old car is going to look dirty pretty quickly, but you’d be safe to leave it in there at least 3,000 miles.

Don’t be fooled into thinking a visual inspection of your fluids means they don’t need to be changed.

It is amazing the cars that make it to 150k with nothing but oil changes.

My neighbor recently traded in his 2001 Prius at over 300K miles, and I’m almost sure it was on all original fluids. Of course that Hybrid Synergy Drive CVT doesn’t exactly have trans fluid though.

My coworker’s son-in-law had such a Prius: bought new, ran to the ground with nothing but oil change, overdue at every change.

It took him around 320K miles to get that car to the point where it died on the side of the road, he walked and bought a new one, same maintenance routine.