Lifetime transmission fluid? Depends on your definition
Sealed units sound good, but need checkup
More and more automakers are delivering lifetime-fluid transmissions in their products every year. From econoboxes with continuously variable units to multi-speed wonders in more expensive rides, suddenly engineers believe they have developed foolproof creations that need no maintenance.
It’s a great marketing feature, but does it hold water?
Transmission fluids do much more than simply lubricate the moving parts inside their gearboxes. They also transform the harsh power output of the engine’s crankshaft into a smoother application via the torque converter. And they prevent excessive wear on the large number of clutch plates and discs involved in providing power to the driveshaft(s). All this activity takes place in a case made of aluminum.
The biggest killers of automatics are excessive heat and contamination (mainly metal filings). If you remove the lower access pan from any automatic transmission, you will find a magnet stuck to the bottom. These small, loonie-sized units will be covered in a layer of metallic powder. If any metal fragments (of any size) are stuck to this magnet, it usually means the transmission is destined for a short life. Transmission filters are located very close to these magnets, not only to strain material out of the flow, but to position the flow in such a way that the magnet can attract and trap any metal in it. These filters can only collect so much of these filings before they overload and start inhibiting normal flows. And as anyone who has played with magnets can tell you, once they collect enough material, they start to lose their ability to attract any more.
So why the no-fluidchange label? For heat, one of the main culprits of transmission fluid failure, all of these lifetime-fluid transmissions have fluid temperature sensors. When this fluid reaches a critical level, the control computer will lock the transmission into a lower gear and flash a dash warning light, making further operation very unpleasant. In drastic conditions, this gearbox electronic module can actually prevent the vehicle from restarting until repairs are completed. But none of this technology will eliminate risks from metal filing accumulation.
Are the automakers promoting their expectations of their transmissions’ lifetimes, or yours? As we are keeping our vehicles almost 10 years on average, with accumulated distances of well over 250,000 km, it’s a good question to ask. Remember the carmaker is only responsible for a fraction of that time/distance (and then only for warrantable defects).
You can change the fluid and filter on these units if you wish, but would be well advised to get an expert opinion on the fluid’s current condition first. These fluids can run $50 or more per litre (most gearboxes take five to 10 L for a normal service replacement) and often the filters are only available with the pan attached (again, rather pricey). Like a sommelier, a good transmission tech can speak volumes about a transmission’s condition based simply on the smell and appearance of its fluid.