Transmission oil change intervals

[Peter C]

Getting off the track a bit here but in 2003 I bought a 1988 manual Corolla with over 300Km from a friend for a few hundred. New brake hoses and tyres to pass the RWC. Not exciting to drive but it ran well until it got rear ended in 2014. Suspension components were still original and roadworthy.

 

[Kim Luck]

Although auto transmission fluid, like engine oil, has additives. Wouldn't these "wear out"?

Not necessarily, additive packages can be very specific but as ATF's are not subject to combustion they can have a very long life.

 

[Wildebeest]

Many thanks for the encouraging replies. But I do miss my 504

 

[JoBo]

Not necessarily, additive packages can be very specific but as ATF's are not subject to combustion they can have a very long life.

If you don't drive It's the heat that kills the oil's vital properties.

 

[Kim Luck]

If you don't drive It's the heat that kills the oil's vital properties.

No it isn't. Oils of every kind are formulated to do a specific job. Looking at a normal type of ATF, here's what it might contain":

Phosphorous - 0.3% AW additive
Zinc - 0.23% AW additive, anti-oxidant as ZDDP
Nitrogen - 0.9% AW additive
Boron - 0.16% Detergent and AW additive
Calcium - 0.05% Detergent/Dispersant, tbn base chemistry
Magnesium - 0.05% Detergent and base chemistry
Sulfur - 0.55% FM and AW
Barium - various% used as particulate control

So where is the ingredient that fights heat? It's called "Oil" and it acts as a coolant.

 

[JoBo]

I've been through all that with the AD4. Repaired and overhauled a few. Checked running temp with original set up and with added air to air oil cooler. Once i fixed the hot running problem and the correct plate clearances, it was a very smooth and lasting transmission.
Have a look at the oil of a hot running AT.
I'd bet London to Brick that you are missing (omitting) something. Transmission oil does deteriorate relatively quickly when they run over 100 deg C - even the synthetics, while they last longer, aren't going to last forever.
Many cars have a water/oil cooler. At what pressure do modern cars run their cooling system in order to raise the boiling point? You work it out?

 

[Kim Luck]

I've been through all that with the AD4. Repaired and overhauled a few. Checked running temp with original set up and with added air to air oil cooler. Once i fixed the hot running problem and the correct plate clearances, it was a very smooth and lasting transmission.
Have a look at the oil of a hot running AT.
I'd bet London to Brick that you are missing (omitting) something. Transmission oil does deteriorate relatively quickly when they run over 100 deg C - even the synthetics, while they last longer, aren't going to last forever.
Many cars have a water/oil cooler. At what pressure do modern cars run their cooling system in order to raise the boiling point? You work it out?

From a U.S. site: For automatic transmission fluids, the Level of Specification, whether it be a DexronIII(H), a Mercon variety, Toyota T-IV, Honda ATF-Z1, or whathaveyou, DOES NOT specifiy the base oils. The fluid developer must come up with a fluid that meets the specification for oxidation resistance, friction modification retention, etc.

Usually, an additive company like Afton (formerly Ethyl) or Lubrizol, or Infineum, or XYZ, comes up with an add pack for that specification. They then suggest a base oil mix for that formulation. The formulation gets tested, and if it passes, everything is hunky dory. Usually, it doesn't pass the first time and has to be tweaked for various reasons, such as for example, friction modification retention. After testing, the additive supplier is confident the additive package can meet the specification requirements for various base fluids. As the specification heat is turned up, higher Group fluids must be used, such as Group III minimum, in order to pass certain tests.

From which I determine that insufficient cooling rather than oil specification is the problem with the transmissions you are concerned with.

 

[Beano]

I omitted mentioning that I will be installing an external transmission cooler. Have had it stored away for a while just for this car.

 

[JohnW]

504 with BW 35 without drain plug.
Remove one of the oil cooler pipes from radiator, start engine allow oil to run into a container, preferably one with level marks. Stop engine when fluid ceases running. Refill with measured amount drained. Repeat if oil is discoloured/smelly.

Off topic. Now that I've entered into Non Froggy ownership ]2005 Toyo Corolla] Dealer service advises of the not necessary to change auto trans oil ?
Anyone...

Good to hear you are mobile again. I'll bet there's a Toyota forum with all the same discussions about transmission fluid changes....

 

[Frenchiemech34]

I have taken a similar approach with my Laguna which supposedly has "sealed for life" transmission. I had the fluid changed at around 100,000k.

Ian.

All aisin Warner transmissions both Peugeot Renault Citroën Volvo should have gearbox oil changed every 60km. Some have in book after lots of issues with valve bodies and solenoids failing. Most Volvo 6 speed autos identical to Peugeot’s n Citroen’s. Tf80sc or AM6.

earlier 5 speed box in Laguna and Saab and others was also meant to be done at 60k.

non servicable filters are reason for this.

tim - Peugeot Citroën master tech and euro specialst mechanic.

 

[Frenchiemech34]

4hp20 and al4 boxes should be done every 40km due to the shift issues they have. Mainly the al4 is the problem child Though being a Renault box lol. Sorry Renault owners.

 

[jackpos]

My last two Volvos have had “sealed for life” transmissions. I choose to change the relatively expensive fluid every 40 -50k. First car was still going fine at 225k, the current one due now at 150k, but still fine. Seems like relatively cheap insurance. They may be sealed for life, but really this just means it will most likely get through the warranty period.

If your Volvos have Aisin 6-speed auto transmissions, according to Aisin they should have the fluid changed every 20,000 kms.

 

[jackpos]

If your Volvos have Aisin 6-speed auto transmissions, according to Aisin they should have the fluid changed every 20,000 kms.

 

[GRAHAM WALLIS]

ZF boxes in 205 and 405 have drain plugs, maybe these cars were designed to go for longer than the newer ones?

 

[Aln]

If your Volvos have Aisin 6-speed auto transmissions, according to Aisin they should have the fluid changed every 20,000 kms.

If you were paying the Volvo price for the fluid for the the Aisin box of around $430 I would surely go broke. Labour is extra. The correct non Volvo ATF is Mobil 3309, about $240 for 20L. Enough to flush and fill twice. So it is a mystery why Volvo say not to bother about changes and Aisin are pushing very regular maintenance. My Volvos were both bought at around 90k, had never had their ATF changed and it was quite discoloured when drained. Subsequent changes are much less so as expected. The gear changes also became a little smoother, but it is hardly a harsh box.

 

[Haakon]

4hp20 and al4 boxes should be done every 40km due to the shift issues they have. Mainly the al4 is the problem child Though being a Renault box lol. Sorry Renault owners.

It was made by Siemens for Renault and PSA. It’s as much a PSA unit as Renault.

Renault however got its use correct, filling them with ELF fully synthetic fluid which gave them massively improved reliability and longevity over the ones fitted to PSA vehicles with a mineral fluid.

Sorry PSA owners

 

[JohnW]

4hp20 and al4 boxes should be done every 40km due to the shift issues they have. Mainly the al4 is the problem child Though being a Renault box lol. Sorry Renault owners.

And here was me thinking it was designed by Siemens....

 

[Whippet]

Hi.

I have a different perspective to many posts here. I have the view that many gallons of good and serviceable oil are replaced unnecessarily, in both engines and transmissions. The major reason that ATF degrades is due to overheating of the fluid. Once the ATF has been overheated it can't recover, so my approach would be to prevent that occurring. The major source of heat input is the torque converter providing torque multiplication from the engine output to the gearbox input, as this process is inefficient, the energy not transferred causes the oil to heat up. So during acceleration, and towing, torque converter action will at its greatest. Later Auto gearboxes have lock up torque converters so when in this state there is 1:1 torque transfer and no slipping to generate heat.

The ATF to engine coolant heat exchanger in the bottom of most radiators can never cool the ATF lower than the coolant temperature. On a hot day towing up a hill the temperature difference and the heat transfer capacity can reduce if the radiator cant dissipate the heat from the coolant, from the additional loads on the cooling systems: hotter engine, AC condenser, warmer ambient temperature to start with.

Instead of wasting money and gallons of oil on frequent oil changes, I would be fitting an additional external ATF cooler. This will assist to keep the ATF below the temperature point where it starts to oxidise, and then cause the other consequential effects: varnish formation, lubricity breakdown, hardening of seals, loss of viscosity and associated loss of clamping force for clutches, then slipping clutches etc. Once these have occurred the damage is done and no amount of frequent oil changes will resolve this.

As to oil that is discoloured (mostly from suspended particles), but not burnt oil, and there is a difference; I am happy to leave it. Automatic transmissions have the advantage over engine oil, in that combustion deposits are not present. Discoloured oil is OK as it's performing the functions that are needed including: lubrication of sliding surfaces, preventing corrosion, dissipation of heat, flushing away worn and liberated particles, hydraulically applying clutches and bands, transferring kinetic energy in the torque converter etc. The filter should be sized to prevent particles that are large enough to cause shuttles, spools and solenoid valves to not operate from being supplied to the galleries.

As to the Aisin advertisement to recommend 2 year / 20,000km changing ATF, well they have a vested commercial interest don't they. There will be a sales and marketing strategy to transfer revenue from someone else's pie graph into the Aisin revenue pie graph and increase their EBIT. I note the advertising flyer has the usual marketing words, like: reduced, longer, better, more responsive, improved feel to try and obtain emotional engagement and buy in. At the end of the day, marketing is marketing, its purpose is to influence behaviour of the target audience.

For those owners that choose many infrequent oil changes, just tell me which oil brand you use, and I will buy shares in that company and encourage you (marketing) to change it even more frequently than you do now, it can't hurt surely?. We both win, you get a warm fuzzy feeling in your stomach and my bank balance increases.