Trans Fluid - to flush or Replace?

unbeatabull, Jun 22, 8:12am
So I know some manufacturers recommend flushing, others recommend dropping the pan.

Car in question is a 300zx, Auto, was wandering if anyone knows which is "recommended" by Nissan, or which would be the better of the two to do. I know I would prefer to just replace the fluid cause its a damnsight cheaper then paying for 12+L of DXIII for the flush! lol Even at staff price it adds up quick.
unbeatabull, Jun 22, 8:12am
Oh, and also, if anyone knows if there is any particular additive you are suppose to add! Or just the standard Wynns Trans Flush/Additive that we chuck in all our cars be ok!
franc123, Jun 22, 8:29am
To do the job properly you should do both, the problem with most autos is the converters are not drainable.Drain the casing it and get the pan off, replace the filter and gasket, perform any adjustments (if any, not many late model ones are), add a couple of litres of new fluid, run it and flush it via the cooler until you get clean fluid out, top it up the necessary amount, reconnect the cooler line, run it again and cycle up and down the gear selector positions a few times, and then add more fluid to at least the cold mark or else just into the area between the marks or hatched area on the stick.Go for a drive of at least 8-10k and recheck the fluid level again, it should be closer to the hot mark or else add more fluid until it is.Check for any leaks.Done.Additives!There are enough additives in the fluid already without adding more to the mix, I wouldn't bother.
unbeatabull, Jun 22, 8:56am
Cheers for that. Guess Ill have to bite the bullet and do the whole shabang
321mat, Jun 22, 11:57pm
NEVER NEVER NEVER flush an automatic transmission.

This is because the "flush" has corrosive particles in the fluid, and these get trapped in the hydraulic lock-up section of the trans, (usually about 4.5 litres), which does NOT drain out when you do a flush,and these same particles will ultimately wear all the arms and sprockets, and before you know it, you will get a really nasty "kick" in the kidneys every time the car changes gear, because the gearbox will become terminally worn.
321mat, Jun 22, 11:58pm
Put some Dr Tranny Shudder Fix in the transmission, this will really smooth out everything, and drastically extend the life of your gearbox.
johnf_456, Jun 23, 12:02am
Do not flush it, just change the fluid
321mat, Jun 23, 12:03am
Oh, and MAKE SURE you use a top of the range transmission fluid - with a DEXRON III (make sure it's 3) rating.
321mat, Jun 23, 12:03am
AGREED.
pandai, Jun 23, 12:06am
I was under the impression that a transmussion flush is typically just 3 drain and refills.Changing the fluid alone will only get rid of a third of it.Don't bother with any magic products in little bottles.
ceebee2, Jun 23, 1:27am
The "flushes" I have done are simply to disconnect the cooling pipes from the trans cooler, hook one to a decent funnel, the other drains into an oil pan,fill the funnel to the brim, get someone to operate the engine and keep filling till the fluid is new looking. Beware that the trans pumps alot of fluid out so do not let fluid level drop below min (Empty funnel). Next remove sump / replace filter and refill as others have explained above. Cheaper than Garage flushing. You will need 20L Dexron III or equivalent. I do not advocate any additives.
For anyone with tiptronic nissans you must use the genuine Nissan oil or trans failure will result. If in any doubt check with the local Franchise dealer.

Cheers CeeBee (Auto Tech 30 years)
intrade, Jun 23, 2:08am
here is what you need to purchase. a sump gasket 10$ a trans fluid filter that is inside the trans 26 to 45$ and 12 liter minimum dextron 3 so you want 3 times 5 liter containers from supercheap auto on special works oit 7 bux a liter so it be sbout 110$ for atf-fluidyou then put car on hoist drain fluid change sump filter refit sump sparkeling clean and adjust the bands befor you refit the sump plate if the bands are adjustable some are some not. like 1998 mazda capella have band adjustment for a example.
then after sump is back on with new gasket you fillliter in the sump thru filler -dipstick usually. Now you go and flush the system by removing the return line from the trans cooler and firing up the car and running it till the fluid is clear dextron. repeate with another 4 liter in thru filler if it runs out before its clear. Now reconnect hose from trans collerfill to correct level on dipstick by filling in 1 liter increments and dont forget to shift thru the gears . after that your all done testdrive and recheck fluid level on dipstick.
That is how you service a auto trans correctly. and as per post 13* is also correct just flushes befor i rather flush with new filter
321mat, Jun 23, 2:30am
I would agree with you on any other occaision, BUT.

Having used Dr Tranny "Shudder Fix" on many occaisions, I can honestly say that is has improved my driving enjoyment amazingly well.The gear changes are smoother, and the feeling of a rear diff "binding" has gone completely.

It IS an excellent product.
ceebee2, Jun 23, 3:26am
Just a note for you intrade that your method will soil a clean filter with dirty oil whereas my method will remain clean.
intrade, Jul 16, 1:48pm
you recon the dirty oil will drip back down! i never had anything flow back down when i replaced the filter, and the fluids get pumped from sump thru torque converter to transcooler and then back in a bucket before it returns to the sump. I cant guarantee it wont soil the new filter but in my opinion it dont and if so minimal.