[SOLVED] Calculation question (probably simple, but I'm bad at it)

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Bobb24
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by Bobb24 »

I have always wanted to know but was too lazy to try to figure it out... until now. Never been able to figure out the slide ruler thing. I used 25% and 1000ml for simplicity

How much new fluid does it take to replace old fluid of 1000ml capacity if only able to remove and refill 250ml at a time ?
1 1000-250=750 add 250 =1000ml (750ml old+250ml new)
2 750ml old fluid +250ml new fluid diluted by 25% =
Old New
750 x .25 =187.5 250 x .25=62.5
750-187.5 250-62.5
=562.5 =187.5 + 250 = 437.5 + 562.5=1000ml

562.5ml old,437.5ml new
562.5 x .25=140.625 437.5 x .25=109.375
562.5 – 140.625 437.5 – 109.375
=421.875 =328.125 + 250 = 578.125 + 421.875=1000ml

421.875ml old, 578.125ml new
421.875 x .25=105.46875 578.125 x .25=144.53125
421.875-105.46875 578.125-144.53125
=316.40625 =433.59375 +250 =683.59375 + 316.40625=1000ml

316.40625ml old, 683.59375ml new
316.40625 x .25=79.1 683.5937 x .25=170.9
316.40625-79.1 683.5937-170.9
=237.31 =512.7 + 250 =762.7 + 237.31=999.8ml

237.31ml old, 762.7ml new
237.31 x .25=59.3275 762.7 x .25=190.675
237.31-59.3275 762.37-190.675
=177.98 =571.695 + 250=821.695 + 177.98=999.675ml

177.98ml old, 821.695ml new
177.98 x .25=44.495 821.695 x .25=205.42
177.98-44.495 821.695-205.42
=133.485 ==616.275 + 250 =866.275 + 133.485=999.76ml

133.485ml old, 866.275ml new1000ml
133.485 x .25=33.37 866.275 x .25=216.57
133.485-33.37 866.275-216.57
=100.115 =649.7 + 250 =899.7 + 100.115=999.81ml

100.115ml old, 899.7ml new
100.115 x .25=25.03 899.7 x .25=224.925
100.15-25.03 899.7-224.925
=75.12 =674.775 + 250=924.775 + 75.12=999.895ml

75.12ml old, 924.775ml new1000ml
75.12 x .25=18.78 924.775 x .25=231.19
75.12-18.78 924.775-231.19
=56.34 =693.585 + 250=943.585 + 56.34999.925ml
It has taken 2500ml new fluid to get to a 95% new fluid mixture

I did this manually in Libre Writer and copy and paste threw off the format, hope you can follow
Bobb24
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by Bobb24 »

I think the point is that you have to keep using your diluting percentage and apply it to both new and used fluid ratio at each step.
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by slipstick »

Bobb24 wrote:
Tue Sep 01, 2020 8:05 pm
I have always wanted to know but was too lazy to try to figure it out... until now. Never been able to figure out the slide ruler thing. I used 25% and 1000ml for simplicity

How much new fluid does it take to replace old fluid of 1000ml capacity if only able to remove and refill 250ml at a time ?

=56.34 =693.585 + 250=943.585 + 56.34999.925ml
It has taken 2500ml new fluid to get to a 95% new fluid mixture

I did this manually in Libre Writer and copy and paste threw off the format, hope you can follow
Slide rule works for this too.
* runner to .05 on the inverse LL3 scale under the hairline
* move slide to bring right index of C under the hairline
* move runner to place hairline over .75 on the inverse LL2 scale
* read 10.41 under the hairline on the CI scale (calculator says 10.4133...)

So it would take 10.41 refills, or 2600 ml.
or, looking at it the other way around, 0.75^10,41 = 0.05005, or 94.995 % new fluid mix.

How this works:
we want to find x where 0.75^x = 0.05
we know that .75^x can be expressed as e^(x*ln(.75)) and this = .05, so we can take the natural log of both sides and get x*ln(.75) = ln(.05) and solve as x = ln(.05)/ln(.75)
this can be written as ln(.05)/x = ln(.75)

runner hairline to .05 on inverse LL3 puts ln(.05) under the hairline on D - we then move the CI index to this number
now moving the hairline to .75 on inverse LL2 multiplies the number at the CI index by 1/x with x on CI to give the result ln(.75) under the hairline on D. We can read x on CI under the hairline.

Easy, peasy! :D
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by Lert »

All this slide rule talk is making me nostalgic for my now lost Hemmi Bamboo.
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Re: Calculation question (probably simple, but I'm bad at it)

Post by antikythera »

DAMIEN1307 wrote:
Tue Sep 01, 2020 1:37 pm
HINT...The slow steering back and forth ensures that you will bleed any air out of the system while "basting" the turkey...lol., as well as insuring the new fluid has access to the entire PS system while expelling the old fluid.
This is essential as you will get air in the system, it cannot be avoided (especially with repeatedly dipping in a turkey baster) or any other filling implement of choice. Should you get bubbles or pockets of air in the steering system it will undoubtedly become noisy, notchy and eventually difficult to turn the wheel properly which is quite frankly dangerous.

Just like you have to bleed brakes when changing brake fluid, both are essential to your safety and everyone elses in the vicinity of your car. Both faults would be an MOT fail in the UK.
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Re: Calculation question (probably simple, but I'm bad at it)

Post by Pjotr »

antikythera wrote:
Wed Sep 02, 2020 4:16 am
DAMIEN1307 wrote:
Tue Sep 01, 2020 1:37 pm
HINT...The slow steering back and forth ensures that you will bleed any air out of the system while "basting" the turkey...lol., as well as insuring the new fluid has access to the entire PS system while expelling the old fluid.
This is essential as you will get air in the system, it cannot be avoided (especially with repeatedly dipping in a turkey baster) or any other filling implement of choice.
I disagree.... When the steering wheel stays motionless during the operation, the turkey baster will only suck up what's in the reservoir. It'll only touch the surface of the fluid, so to speak. Not what's deep down in the power steering mechanism itself.

When the reservoir is afterwards replenished with new fluid, there's practically no risk that any air will enter the mechanism.

The only downside is that the refreshing is less effective, because less old fluid is being removed with a motionless steering wheel. Only the 200 CC in the reservoir. Hence the need for several repetitions (with the car being driven between each operation, so that the fluid mixes well).
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by Pjotr »

Completed the fourth refreshing today, which has reduced the percentage of old oil to approximately 28 %. The fluid I removed was so clean, that I've decided to skip the fifth refreshing.... Started to feel like a waste of time, energy and good ATF to continue.
Last edited by Pjotr on Thu Sep 03, 2020 2:48 pm, edited 2 times in total.
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by cliffcoggin »

I have just realised I misread the original question. Somehow I got it into my head you were asking about brakes rather than power steering. Oops.
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by kelevra »

Pjotr wrote:
Thu Sep 03, 2020 9:34 am
Completed the fourth refreshing today, which has reduced the percentage of old oil to approximately 28 %. The fluid I removed was so clean, that I've decided to skip the fifth refreshing.... Started to feel like a waste of time, energy and good ATF to continue.
Being a master automotive technician (what was drilled into our heads) or just a plain old mechanic, I was always taught that a flush will never completely remove all the old fluid. A flush is only meant to replenish the additives in the fluids that are 'burned off' in the repeated heat cycles experienced by drivetrain components. There are exceptions to the rule of course. An old-world coolant flush comes to mind. (remove the thermostat and all drain plugs, install water hose to inlet heater hose and run engine until the fluid runs clear, drain and replace components then refill system) This is not environmentally feasible in today's world. In today's world, one must use machines to perform flushes and recover the old fluids for recycling.

What you're doing Pjotr is a perfectly acceptable method of refreshing your PS fluid. There are sealed automatic transmissions that have a similar method of "flushing" their fluid. Even the above mentioned brake system flush will never truly replace all the fluid. It will, however, remove enough hydroscopically contaminated fluid to make the system safer. Brake fluid is hydroscopic and absorbs water from the atmosphere. Water in a brake system will boil and create air bubbles.
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by Pjotr »

kelevra wrote:
Thu Sep 10, 2020 3:57 am
What you're doing Pjotr is a perfectly acceptable method of refreshing your PS fluid. There are sealed automatic transmissions that have a similar method of "flushing" their fluid.
Good to hear! I've also used this turkey baster method for flushing the automatic transmission of both my cars, even though they do have a drain plug for that. Less messy this way.

As with the power steering fluid, Toyota claims that changing the oil in the automatic transmission is wholly unnecessary, because that oil should last for the entire lifetime of the cars as well (a Yaris from 2000 and a Yaris from 2001). However, I think it was a sensible preventative measure to flush it anyway, because my wife and I intend to keep using them for a very long time.

They've already been driven for about 250.000 kilometres each, and we want to continue using them until they've at least reached 500.000 kilometres each. The "entire lifetime" mentioned by Toyota is probably not intended to cover that kind of mileage. :mrgreen:

For flushing the automatic transmission I used one can Toyota ATF type T IV of five litres for each car, which allowed for two flushes. Thus I reduced the amount of old ATF to (if I recall correctly, I don't remember the exact figures) something like 25 %. The fluid became much clearer this way: there was a noticeable reduction of pollution.

In fact, I've been using the turkey baster method for changing the engine oil as well. Not for consecutive flushing, but simply one extraction (which gets about 80 % of the old engine oil out in one stroke) and then the replenishing with new oil. Been doing this for years, once a year.

Very cheaply, because I buy high-quality synthetic oil (Valvoline 5W-40) for a ridiculously low price at a discounter. Every couple of years I replace the oil filter as well.
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by kelevra »

Pjotr wrote:
Thu Sep 10, 2020 4:54 am
Very cheaply, because I buy high-quality synthetic oil (Valvoline 5W-40) for a ridiculously low price at a discounter. Every couple of years I replace the oil filter as well.
I would replace the filter when you do the oil. Most oil filters have a built-in bypass system so that if the filter becomes too contaminated, they will still allow the oil to flow. This will save the engine from oil starvation but obviously allows dirty oil to flow.
Pjotr wrote:
Thu Sep 10, 2020 4:54 am
Toyota claims that changing the oil in the automatic transmission is wholly unnecessary, because that oil should last for the entire lifetime of the cars
Ford makes the same claim with their F150s, claiming it is a "lifetime" fluid. They even stopped putting visible dipsticks on them. It has been a few years since I 'retired' and they could have retreated on this claim. IDK
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by Pjotr »

kelevra wrote:
Thu Sep 10, 2020 7:33 am
I would replace the filter when you do the oil.
I'll consider that. Thanks for the advice.
kelevra wrote:
Thu Sep 10, 2020 7:33 am
Ford makes the same claim with their F150s, claiming it is a "lifetime" fluid. They even stopped putting visible dipsticks on them.
That's crazy.... So it's entirely inaccessible. :shock:

I very much doubt that that "entire lifetime" claim applies to mileages over 200.000 kilometres / 124.000 miles.

In a new automatic gearbox, there'll be generated relatively much pollution in the beginning, because the moving parts will have to get "tuned" to each other by wearing a little. So it makes sense to flush that automatic transmission at least once in its lifetime, preferably after some 50.000 kilometres / 31.000 miles, in order to get rid of that initial pollution load. At least when you aim to get "extreme" mileage out of your car....
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by kelevra »

Pjotr wrote:
Thu Sep 10, 2020 8:43 am
That's crazy.... So it's entirely inaccessible.
Not entirely, they hid it beside the RH catalytic converter where the heat is smokin'. It is a little plastic one that you unthread.
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by antikythera »

Ford F150 like this one? :lol:

It made me laugh when Ford took legal action against Ferrari to prevent them using the F150 name on their F1 car to celebrate the 150th anniversary of Italian unification that year. The similarities between the F1 car and a pickup are so obvious...
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Re: [SOLVED] Calculation question (probably simple, but I'm bad at it)

Post by kelevra »

Sadly, nothing like that one.
Ford and Ferrari have a long-standing dislike of each other. It is too bad the issue had to be resolved with a lawsuit.
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