which is better, thicker or thinner atf.

mjwcookie Seriously Crusin Dubber

105 posts · joined Mar 2011 · 30 Jan 2012, 11:02 pm

#884420

I have an old transmission 090 in a 89 t25. on starting cold, it goes nowhere and seems to wait a bit to let the pressure build up. after a few minutes is is ok but siwtching gears takes a bit longer. If it has gone cold after a drive (say 4-8hours) same problem. whines a bit in park and reverse when cold. i am contemplating a rebuild or a second hand one, but funds not there yet.

i have tried changing the fluid and it is better in the short term. when i add an atf fluid additive is seems better but that too soon stops.

my question is which is better for an old transmission. thick or thin atf?

Mark Wilson
78 bay window, 82 bay Westy. T3 Caravelle GL 89 on the road.
Now in Victoria.

bajachris88 The international telephone dialing code for Antarctica is 6

6,661 posts · joined Apr 2005 · 31 Jan 2012, 6:00 pm

#884519

thicker stuff usually raises temperatures, but its greater viscosity allows it to fill the 'voids' or clearances that are now greater because of the wear and tear, thus being like a liquid gap filler 🙂.

The principal works for motors, i can only assume it would be the same for an old auto transmission. Best to wait for a expert opinion though.

(ô_!_/ô) (ô_!_/ô)
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68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 · 31 Jan 2012, 9:15 pm

#884584

mjwcookie wrote:I have an old transmission 090 in a 89 t25. on starting cold, it goes nowhere and seems to wait a bit to let the pressure build up. after a few minutes is is ok but siwtching gears takes a bit longer. If it has gone cold after a drive (say 4-8hours) same problem. whines a bit in park and reverse when cold. i am contemplating a rebuild or a second hand one, but funds not there yet.

i have tried changing the fluid and it is better in the short term. when i add an atf fluid additive is seems better but that too soon stops.

my question is which is better for an old transmission. thick or thin atf?

I believe thicker ATF if You can find it?
for it to be pumped in a worn system.

same as engine oil..
in a worn engine...

Lee

- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

ducati998 Commited Dubber

53 posts · joined Apr 2010 · 1 Feb 2012, 6:03 am

#884612

The transmission needs to be rebuilt. The seals in the clutch packs have gone hard. So what is happening is the oil is going past the seals and not appling the clutch. Once the transmission warms up abit the seals become soft and
start to do there job again. You can not buy thicker ATF oil. The difference in oils are the additives that the car manufactures use. Most of the time changing the oil makes the problem worse.

BRUTUS Officially Full-On Dubber

255 posts · joined Feb 2006 · 3 Feb 2012, 12:58 pm

#884975

There are differences in actual oil viscosities between various types and brands of ATF's. But you need to be using the correct type specified for the transmission.
When you change the oil, you need to check that the screen/filter is clear, and clean out the pan. (You may be able to get 'oil flush' I think to clean the system before draining it, but I don't know the brand.)

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