e-man

Hey guys. Generally speaking, how often are you supposed to change/flush coolant, automatic transmission fluid, differential fluid, and brake fluids?

I have a 99 GS400 with 124,000 miles. The dealer has quoted me over $1,000 for the 120k service, but I just changed all these fluids at 95,000 miles (when I did the timing belt, water pump and spark plugs), and I'm not sure that it's necessary to change all of these fluids again now. Thanks for any help.

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gypsyjimi

Here's a guide straight from Lexus (2000)

Ryeno

iTrader: (3)

The easiest way to remember is.

oil every 5k miles

Power steering, Brake Fluid, Coolant, Tranny/differental fluid every 3yr or 30,000 miles. Truthfully lexus coolant is supposed to be good for 5 years. But basically just do that and you'll be good.

Personally i like changing oil on 000 exactly so i remember every 5k i need a change (ex. 120k, 125k, 130k). And same kind of logic with all the major fluids. Do them all at 120k, so i can do them again at 150k then 180k etc.

PushinLEX

iTrader: (9)

Hold on man. I know brake fluid has to be changed around 30k intervals. But from what I hear coolant, tranny, and differential fluid can go for a good 60K +?

Can any mechanics chime in?

Ryeno

iTrader: (3)

Truthfully brake/clutch fluid never really needs to be changed. It's just advised.
Coolant can go up to 5 yr or 50,000.(toyota red long-life coolant) Well atleast thats what toyota says. IDK if i trust that tho. I've heard stories of the coolant failing before the 50,000k mark.
As for tranny/differental/power steering fluid. I'm not sure what the max life of them are. But a lot of people neglect those fluids. If you change them every 30k, you'll be straight.

mitsuguy

iTrader: (2)

Incorrect about the brake/clutch fluid. Brake fluid has corrosion inhibitors that wear out over time. Once these corrosion inhibitors are worn out, they start eating away at the brake components. For instance, the guideline used is how many parts per million of copper are present in the fluid. If it gets so corrosive as to leech the copper out of the metal hard lines, imagine what it is doing to the rubber components (lines, caliper/master cylinder seals, etc.)

Here's some good info on coolant: http://www.google.com/url?sa=t&sourc...r5daftkuGErvRA

What I really don't understand, and maybe Toyota has a good reason for it, is the different coolant replacement suggestions depending on the car. For instance, 2006 Toyota Camry calls for 30k coolant replacements with super long life, however, a 2006 Prius calls for it's first coolant replacement at 100k, with subsequent replacements every 50k...

Ryeno

iTrader: (3)

Your 3rd paragraph is what i mean about never needing to change the brake fluid. Like you could not change anything but motor oil and your car could run to 120k no problem. It's weird and very hard to predict exactly when a fluid will stop protecting.

Thats why i say just change at every 30k miles. Infact the only time most people even get their other fluids changed is when the guy changing their oil, tells them to.

mitsuguy

iTrader: (2)

It's not hard at all to tell when these things stop protecting. There are tests for most of them. There are test strips for both brake fluid and coolant to test copper content in the brake fluid, and the acidity of the coolant. This easily tests how much protection they are giving. Trans fluid is somewhat harder, as is oil, but they can be sent out for analysis.

Here's a site I found just now with some info on the brake fluid: http://www.gwrauto.com/stripdip.htm
and the same place, some additional info on the coolant test strips: http://www.gwrauto.com/RadStrip1.htm

edit: and as far as lasting til 120k, there are a lot of people that would tend to disagree with you. I have no clue how many water pumps, radiator hoses, radiators, wheel cylinders, calipers, master cylinders, etc, all on vehicles with less than 100k miles. I know a lot of repairs are not avoidable, but I do fully believe if my customers would be a little more pro active in maintenance, I wouldn't be repairing their cars as often...

Kostyan

I think more of a common sense need to be applied here. Lexus wants you to be at the dealer paying $$$ for that damn fluid change. Fluids themselves are not cheap. Changing brake fluid every 30k mi is excessive, and 100k mi is more reasonable. Coolant can last at least 50-60k mi, thats when it need to be drained from the radiator, and around 100k mi the entire system can be flushed.

mitsuguy

iTrader: (2)

You just making these numbers up, or do you have something to substantiate them.

All of the fluids should be replaced when they can no longer perform their intended purpose.

Brake fluid becomes very caustic and starts eating away at internal brake components, the parts you can't inspect, so, it should be replaced when it becomes caustic - there are tests, as mentioned above. My experience has been that this occurs approximately every 2 years, or 30k miles, so, experience matches recommendation.

On coolant, if using green ethylene glycol, then 2 years, 30k is when it has typically depleted all of its corrosion inhibitors, however, the Toyota coolants can last 100k, but should still be tested because there is no way to just look at it and tell.

Trans fluid loses it's ability to clean as well as it's friction modifiers break down. I don't know how this is tested specifically, but transmissions are not cheap to replace/rebuild, so I change mine on manufacturers intervals, and use synthetics as well...

Am I saying these things can't be used well past their intended usefulness, no, of course not... but I'd rather prevent water pump, radiator, brake system and other failures by taking care of the lifeline of those components - their fluids....

But on your car, you can do whatever you want...

They say everyone chooses not to do maintenance on their car for one of two reasons - they either can't afford to, or they don't believe the manufacturer/technician/whomever

818sc400

ok let me get this straight.

oil changes every 5k miles
rear diff every 30k
tranny drain every 30k
radiator coolant every 30k
brakes fluid every 30k

i love to do preventive maintenance. soon i bought my car i made sure everything had to be done to get it in best performance shape as possible. treat it right and it'll return the favor

mitsuguy

iTrader: (2)

Sounds like a reasonable schedule to me...

Kostyan

did you perform the tests yourself?
I've owned other makes and their maintenance schedules did not call for replacement of brake fluid every 30k miles. You wouldn't want to say that somehow Lexus put inferior brake fluid in its cars, would you.
I've had cars that were older than 7 and had over 100k mi, but actually had never replaced the brake fluid, and never had any problems.

Now, this is completely different than replacing engine/tranny oil...

mitsuguy

iTrader: (2)

I see, on average, 40 cars a day. I would say I have a pretty good sampling of vehicles, everything from your low end Aveo to 100k + Mercedes... MAP (motorist assurance program), which is a collaboration of car manufacturers, dealers, and independent repair facilities, say that if brake fluid copper content is above 200 ppm, that the brake fluid has lost its corrosion inhibitors and it is a required fluid replacement.

It is not completely different than replacing engine oil or transmission fluid. A good quality synthetic oil breaks down very little over its lifespan, in fact, the viscosity and lubricity of the oils far outlast the additives that are used to keep the engine oil clean and protecting the engine. It's these additives that break down over time as the main reason that we replace oil as often as we do. Quick example off top of my head is Mobil 1 versus Mobil 1 EP - the extended performance has shown to be the same oil just with a different, more robust additive pack. Same with transmission fluid, when we replace it, it is because it is no longer able to maintain its viscosity typically, its because the friction modifiers and detergents have broken down.

Same goes for brake fluid. It will still function, it will just start eating away at the brake systems internals. Many many people get away with it much longer than they should, and a select few suffer the consequences by having to replace master cylinders, calipers, etc.

Not all vehicle manufacturers require these services at all, which keeps the cost of ownership down on that particular vehicle. A $75-$100 brake flush every 30k miles on an Aveo is an added cost of ownership most aren't willing to pay and could steer a car buyer away from it. On a Lexus or other high end car, they go the extra step to ensure that the vehicle has as few problems as possible, which helps their reputation. They do this by recommending preventive maintenance practices for all systems they are able to.

A quick computer search shows that Mercedes, BMW, Audi, Porsche, Volvo, Lexus, Mini, Acura and possibly more all have recommendations to replace the brake fluid, typically at 30k or every 24 or 36 months. Many manufacturers cite "inspect brake fluid" as well, including Hyundai (per their inspection, they want either a copper content or a hygrometer based test).