Xantia - Automatic Transmission Fluid

brmartyn · Unread post by **brmartyn** » 26 Apr 2010, 09:11

brmartyn wrote:Will call my local Citroen dealer in the morning and see how much they charge for the fluid. thanks everyone.

Just called my local dealer £15.98 for a 2L bottle don't think thats too bad to say it's directly from Citroen. Will be popping down at the end of the week and will getting two bottles.

Clogzz · Unread post by **Clogzz** » 26 Apr 2010, 14:13

The PSA AL4 and Renault DPO are the same box.
Renault uses red Dexron III, and LT 71141 is a semi-synthetic undyed Dexron III.

All the stories of LT 71141 being holy water are just tricks to increase our dependency on Citroën and its bedfellows.
Somehow, the Esso container doesn’t have to explain what’s inside.
http://jaguarmark2.free.fr/images/BVA_AL4/al4_huile.JPG

I’ve just replaced the transmission fluid with Penrite ATF BMV … 4 litres for $A50.
http://www.penriteoil.com.au/pis_pdfs/ATF%20BMV.pdf

Unread post by **CitroJim** » 26 Apr 2010, 19:14

Clogzz wrote:The PSA AL4 and Renault DPO are the same box.
Renault uses red Dexron III, and LT 71141 is a semi-synthetic undyed Dexron III.

I wish to very politely say I beg to differ Clogzz. Sorry, the Dexron I have seen and LT are nothing like even if you take the dye away. Dexron has an almost pleasant smell whereas LT smells like, in Hirsty's words, cats pee. Not at all pleasant... In fact it makes you feel sick after a while and every time I have rebuilt a 4HP20 it has made me feel quite nauseous fro a while afterward...

LT is also stickier and thicker. It has a different texture.

Clogzz wrote: I’ve just replaced the transmission fluid with Penrite ATF BMV … 4 litres for $A50.
http://www.penriteoil.com.au/pis_pdfs/ATF%20BMV.pdf

Ahh, now that's fair dos. The manufacturer has stated that the Penrite stuff is to specification for 'boxes needing LT. No worries there.

The clincher in this whole argument, and again made clear on the Penrite application note is that LT711412 can be substituted for Dexron quite happily but this is not reciprocal; Dexron cannot substitute for LT71141.

Clogzz · Unread post by **Clogzz** » 27 Apr 2010, 13:31

Hello Jim,

Please differ, no risk of offence.

The original blackened oil and the Penrite were noticeably more viscous than red Dexron III, but neither stank of cat’s pee like thick differential oil.
I made two oil changes to replace 75% of the fluid.
In case of doubt, we use green Castrol Transmax Z as a does-it-all recipe, but I’m too stingy to pay $A75/£45 for 4 litres.

http://www.castrol.com/liveassets/bp_in ... smax_Z.pdf

Unread post by **CitroJim** » 27 Apr 2010, 17:30

Maybe Esso add the essence of tomcat to their LT to differentiate it; maybe its just a stenching agent similar to that used in natural gas so we can smell leaks and has no purpose except to offend our noses...

New oil seems to me to smell more catty than old. It tends to loose it over time to an extent...

I'm led to believe the horrid smell of traditional gear oil is from the sulphur in it. Sulphur has superb lubricating properties and was always a welcome ingredient in DERV where it lubricated the injection pump a treat. Taht was until they realised that sulphur, water and oxygen make sulphuric acid, otherwise known as acid rain...

John Plum · Unread post by **John Plum** » 08 Aug 2010, 23:28

Oil Store list genuine Esso 71141 @ £122 per 20L. If anyone buys 20L, I would be happy to take 4L at the going rate as I will need to do another partial change in a few weeks.

Count me in the list of customers for bulk-buy purchase please (am watching this topic).

lexi · Unread post by **lexi** » 10 Aug 2010, 23:43

I wouldn't take the chance using the Dexron myself. I would not be surprised if Cloggz was right though.

It stands to reason that as the boxes were "sealed for life" then a semi synthetic was called for. Just in the same way that 10k engine oil changes are dependent on synthetic oil being used.

Many similar ZF boxes have the dexron specified. So what is it about 4HP20 that totally demands the synthetic content? It is also only a semi- synth. That term never designates the percentage of synthetic contained. The difference between the 4HP 20 and the other Dexron boxes in Landrover for one is that the others can be got at to change filter etc.

The whole thing could be a load of Cats P**s

John Plum · Unread post by **John Plum** » 11 Aug 2010, 01:00

Clogzz wrote: LT 71141 is a semi-synthetic undyed Dexron III

This statement is worth confirming (I mean it is possible). I wonder what your source of information is? I think the we can rule out the dye as being relevant at all.

What exactly is LT 71141 HP20, I still don't know, but I can see the Penrite ATF BMV and Castrol Transmax sepc sheets are detailed. Castrol specifies replacement for DexronIII and II fuids which are stated as being conventional mineral fuids, unlike the Castrol Transmax, Penrite BMV and LT 71141 oils.

No doubt, mineral oils could be fine, but perhaps not so good for extended life as semi-synthetic (or the misnamed 'oil for life').

hirsty wrote:
The Dexron will kill your box stone dead very quickly

It would be useful to have some real information as to why this is believed to be so. Whose box was killed by it? How did GSF come to reccomend it?

As a newcomer to the AL4 autobox, it still seems safer to me to use the LT 71141 oil, though I would happily use the Castrol Transmax, I think, after a word with them. I've written to Penrite to ask what they think of their oil as a replacement for the AL4.

Some info I garnered searcing around:

Dexron is a GM standard and the Mercon is the Ford standard for ATF, which were standards adopted by lots of car companies. Which is why replacement oils state Dexron III compatibility (which is also backward compatible with Dexron II), even if semi-synthetic.

Toyota, BMW, VW, Mercedes, Honda, hyundai (and others I suppose) all have uniquely speced fluid, with no real generic substitute for any of them.

Considering faster spinning pumps in the JEEP, demands special lube cuz DEX will foam in that appl.

What we're trying to do is pin down, in a way, what the oil specifications actually are in order to consider alternatives.
On the question of additives, which may have a bearing on long life: No additive can substitute for synthetic oils. Which makes Cloggz statement about LT 71141 being a semi-synthetic undyed Dexron III slightly less true: it may be in terms of oil standards, with specs like viscosity and density, but not overall as a longlife fill and for perormance concerning foaming, for which I reckon merely using dexron III is a dangerous practice.

I am not certain of anything, just my quick thoughts sprung off from what I've heard so far.

Sid_the_Squid · Unread post by **Sid_the_Squid** » 11 Aug 2010, 07:49

Another common misconception, properggated by marketing companies no doubt is that dex3 is a replacement for dex2. It most certainly is NOT.
If one was to believe the hype as it were, one would come to think of Dex3 as this wonder fluid suitable to replace all automatic fluid, this at least seems to be the attitude of most automotive parts shops as well as a lot of thir party garages.

My point being stick with what the box manufactures recommend, a small amount of savings short term could cost you big in the long run. Or to put it another way Dex3 now save £, dead gearbox next year cost £££

Ok rant over

Unread post by **xantia_v6** » 11 Aug 2010, 08:10

The synthetic vs semi-synthetic argument is irrelevant, oils don't wear out. They get contaminated, and sometimes the additive packages undergo chemical change with heat and time.

The critical things with any automatic transmission fluid are the viscosity and friction-modifiers. These are critical because they control the amount of slip between friction surfaces.

In an old-style hydraulic transmission (the sort dextron was designed for), the slip mostly occured between the bands and drums just after a gear change, and the slip was intentional, to slur the change and make it smoother.

In an electronic box like the 4HP20, it appears that the clutches are not designed to slip (much), and the slurring of changes is largely down to the torque converter. The 4HP20 torque converter however has a semi-lock-up clutch, which in normal driving (according to the literature) has a slip of up to 5%. Imagine the effect on the rate of wear of that clutch if the oil has slightly different friction characteristics.

I believe BTW, that a large proportion of 4HP20 failures are due to oil starvation, caused by blocked oil filter, blocked by debris from the torque converter clutch.

Sid_the_Squid · Unread post by **Sid_the_Squid** » 11 Aug 2010, 10:56

After the protective additives break down, contaminating the oil, the base oil itself will start to break down , if the oil is based on a mineral stock it wont last 5 mins, however a fully synthetic oil at base has far greater resistance to heat and sheering (and far fewer additives) therefore will survive for far longer. Choosing weather to purchase synthetic or mineral Gearbox oil should be no different than facing the same choice with engine oil, i.e. the correct oil (meeting all requirements) can be used weather it be mineral or synth, however if its mineral frequent oil changes should be observed to combat the rapid breakdown inherent with such a product.

I imagine Dex 2 is traditionally a mineral based oil, hence why regular oil changes have always been recommended for boxes using such fluid. I suspect the AL4\4HP20 oil is a synthetic base, thus a far longer lasting product, hence the 'sealed for life' myth propagated by some, probably because it will last until outside of the cars warranty time, hence 'life'.

John Plum · Unread post by **John Plum** » 11 Aug 2010, 15:13

oil starvation, caused by blocked oil filter, blocked by debris from the torque converter clutch

...Which brings me back to my horror of dirty oil: a recent change of 50% still leaves filthy stuff. I'll increase it to 75% shortly by adding another 4 literes to a drained box, but I imagine it's still going to be dirty. Wouldn't it be nice to be able to just change or clean a filter?

John Plum · Unread post by **John Plum** » 11 Aug 2010, 15:17

After the protective additives break down..

So, as protective additives cause damage due to relatively early break down, is their protective benefit in the cost/benefit gamble mainly anti-slip, and possibly anti-foam?

Sid_the_Squid · Unread post by **Sid_the_Squid** » 11 Aug 2010, 16:11

Think of it more in terms of protective additives being the first layer of armor once that is gone only the 'base' level remains, the time in which it takes for the base to be defeated depends on its construction. Mineral oil requires more additives and alterations to its structure to reach the required VI rating, and to maintain stability at extreme conditions, synthetics are designed from the ground up to cope with extreme conditions and high durability therefore require less additives, and are less prone to breaking down. This does not mean they cannot be contaminated by external factors (clutch particles, or engine soot) in the same fashion as a mineral oil, what it means is they are less likely to break down under heat or metal sheering. Which is why extended service internals can be specified when using such oils.

Under "ideal*" identical driving circumstances doing 3000 miles using mineral oil will yield the same protection as using a synthetic of the same grade, as both are fresh and fully functional, however once you start hitting 7000 miles the mineral oil will be degraded in lubrication and protection where as the synthetic will not, assuming its not overwhelmingly contaminated by external particles.

To be clear in this instance protective additives refer to the additives put in the oil at construction time by the producers, not to be confused with aftermarket oil additives, which are pure marketing bunk.

There are also a lot more major oil contaminants in an gearbox (clutch particles) or engine (carbon/soot) than will be caused by the oils own break down.

Yes not being able to change the oil filter in these gearboxes without a full strip down is a serious design flaw.

If your interested in reading more about oil, here is a good place to start.
http://www.carbibles.com/engineoil_bible.html

This cut down article is also worth a look
http://micapeak.com/info/oiled.html

I hope this post has made things clearer as opposed to foggier.

*ideal being a warm summers day. Synthetics offer more protection in cold.

John Plum · Unread post by **John Plum** » 11 Aug 2010, 20:04

Thanks Sid, that's helpful.