Transmission Fluid Change Question

[Kilgore Trout]

Over the weekend, I uncrewed the bolt on my auto transmission drain pan, drained out the fluid, cleaned the debris on the bolt magnet, and the put in 4 new litres of transmission fluid in the funnel up top.

The question I have is with the drain and refill method how long do you go before doing a second drain and refill.

i understand with the drain and refill of the pan as opposed to system flush, you don't get any of the dirty transmission fluid in the torque converter. So you have to drive a while so that the dirty oil in the torque converter slushes in and mixes with the oil in the drain pan.

But how long do I have to drive before draining and refilling again. Is one week good enough or should I drive 4000 km before draining and refilling again.

Thanks for any info. I've never changed my own transmission fluid before.

 

[Ceiling Cat]

If you go to a garage they will tell you that you need a full machine flush to get out all the old oil. @ who know how much $$$.
I have changed the oil by draining it and replacing the transmission fluid, and doing a second drain and refill after a month. Then once a year after that. The new transmission oils last a long time, if you drain and refill you are keeping the transmission oil clean.

 

[Kilgore Trout]

Okay, thanks Ceiling Cat. I was thinking along those lines myself.
I was changing my motor oil at one of the chains a couple of weeks ago and the guy asked me if I wanted him to change my transmission fluid for 170 plus tax and I thought to myself why not just change it myself and save a lot of money.
Very easy job to do.

 

[Ceiling Cat]

I wait for the specials on motor oil at Canadian Tire and buy Synthetic. The oil filters are about $5-9 depending on model. I even buy regular motor oil to flush out my engine. First do a conventional oil drain and replacement and run for a week, then do a filter change and change out the motor oil with synthetic. After an oil change my engine oil is so clean I have a hard time checking my dipstick because the oil is so clean. I can do an engine flush and synthetic oil change for under $50. ( if you buy the oil when it is on special. ) A jug of regular oil on special is $10 and a jug of synthetic on special is $25-30. I have 4-5 jugs of synthetic on hand.

 

[Kilgore Trout]

I usually do my own oil changes too; but, last time i wasn't in the mood and stopped at a chain.
Like the motomaster synthetic oil when it's on sale for 40 per cent off.

 

[Ceiling Cat]

I like Quaker State / Castrol synthetic, but I would not hesitate on the Motomaster synthetic it is manufactured by the big oil companies. I have seen synthetic oil at 50% and more discount.

 

[HEYHEY]

I wait for the specials on motor oil at Canadian Tire and buy Synthetic. The oil filters are about $5-9 depending on model. I even buy regular motor oil to flush out my engine. First do a conventional oil drain and replacement and run for a week, then do a filter change and change out the motor oil with synthetic. After an oil change my engine oil is so clean I have a hard time checking my dipstick because the oil is so clean. I can do an engine flush and synthetic oil change for under $50. ( if you buy the oil when it is on special. ) A jug of regular oil on special is $10 and a jug of synthetic on special is $25-30. I have 4-5 jugs of synthetic on hand.

lol
thats a new one

 

[Titalian]

Over the weekend, I uncrewed the bolt on my auto transmission drain pan, drained out the fluid, cleaned the debris on the bolt magnet, and the put in 4 new litres of transmission fluid in the funnel up top.

The question I have is with the drain and refill method how long do you go before doing a second drain and refill.

i understand with the drain and refill of the pan as opposed to system flush, you don't get any of the dirty transmission fluid in the torque converter. So you have to drive a while so that the dirty oil in the torque converter slushes in and mixes with the oil in the drain pan.

But how long do I have to drive before draining and refilling again. Is one week good enough or should I drive 4000 km before draining and refilling again.

Thanks for any info. I've never changed my own transmission fluid before.

Did you change your filter ??

 

[Kilgore Trout]

Did you change your filter ??

No, you can't change the filter when all you do is remove the pan drain bolt and then swap out 4 dirty litres of oil and replace with 4 new litres of trans oil.
The manufacturers put the drain bolt there in case owners want to swap out some of their transmission oil.
To change the filter the whole drain pan has to be removed I believe and that's not something most owners are going to do with their cars.

 

[Titalian]

No, you can't change the filter when all you do is remove the pan drain bolt and then swap out 4 dirty litres of oil and replace with 4 new litres of trans oil.
The manufacturers put the drain bolt there in case owners want to swap out some of their transmission oil.
To change the filter the whole drain pan has to be removed I believe and that's not something most owners are going to do with their cars.

How many kms did you have on the vehicle ?

 

[Ceiling Cat]

Some car transmissions do not have filters.

 

[trm]

Automatic transmission fluid should be replaced every 30,000 miles or 50,000 kilometers.

 

[bestman007]

Transmission fluid should never be changed in most cars. You should never have to break the sealed compartment which contains the transmission fluid.

 

[jcpro]

Transmission fluid should never be changed in most cars. You should never have to break the sealed compartment which contains the transmission fluid.

This. There are mechanics that swear that the transmission fluid should not be changed.

 

[nottyboi]

This. There are mechanics that swear that the transmission fluid should not be changed.

I think they are wrong. No transmission is sealed, they all have air breathing holes. If they did not, the temperature changes will result in pressure changes that will cause them to leak. Is it possible to seal them? Sure but it would make it hugely expensive to manufacture. If you don't change the fluid it is likely the tranny will still get to 160K km with no major issues, but after then, depending on how you use the car, failure rates will start to rise.

 

[Titalian]

I agree with this, after all we are dealing with constant moving parts which equates to wear and tear. The system needs to be flushed and refilled with renewed fluid.

 

[james t kirk]

Check on line to see if the service manual is available.

Many manufacturers have car forums on line. The forums may have copies of the service manual on line which will tell you exactly how to change your transmission oil.

For example, I have an Infiniti G37, which is a piece of shit by the way with the worst transmission in the world. But I can go into the forum and link to the factory service manuals for my model and year car.

 

[spraggamuffin]

Transmission fluid should never be changed in most cars. You should never have to break the sealed compartment which contains the transmission fluid.

Brands like Mercedes Benz advocate this. They don't even bother to put in a dipstick.

Unfortunately, many a transmission has failed just after the warranty period is up or some time after.

Some people have gotten up to 350k to 400k KM on original transmission fluid though.

Many mechanics advise you do at least drain and refills at intervals.

In the lifetime Mercedes Transmissions many were shocked at what they encountered as they delved into the belly of the monster.

A nice syrupy coca cola substance with a burnt smell.

Maintanence is the key to keeping a car in good shape.

What some guys practice may be overkill compared to the basic maintenance needed.

 

[Ceiling Cat]

This is where old info crashes new info. New fluids are different from old fluids. When I had my first car the automatic transmission fluid change was at 80,000 km. There was also this notion that if you had an old car that had old transmission fluid that was never changed past the recommended time it was better to leave it alone. The reasoning is that if you drain the old oil out and put new fluid in, the new fluid had detergents that would wash the dirt off the interior of the transmission and cause it to float around and make problems. The fluids today are different from back 30 years ago, these days many are synthetic and the transmissions are no longer 4 speed automatic and many are 8 steeps dual clutch. The best way to maintain your car is to do as suggested in the manual.

 

[jcpro]

I think they are wrong. No transmission is sealed, they all have air breathing holes. If they did not, the temperature changes will result in pressure changes that will cause them to leak. Is it possible to seal them? Sure but it would make it hugely expensive to manufacture. If you don't change the fluid it is likely the tranny will still get to 160K km with no major issues, but after then, depending on how you use the car, failure rates will start to rise.

One mechanic told me that transmission is like a pair of boots. Once it's broken in, best thing is to leave it alone. My father, who is a mechanic, never changed tranny fluid in any of his vehicles. He did for other people as requested. I've never changed transmission oil on any of my Monte Carlos or Buicks. I never lost a transmission.