Why do car manufacturers remove the transmission dipstick? – Jalopnik

There are two schools of thought behind cars that no longer have a dipstick. Removing this will keep less mechanically minded owners from using the wrong transmission fluid and ruining their entire transmission. Furthermore, by not including a dipstick, manufacturers can make transmissions with tighter tolerances, significantly reducing the chance of leakage – which is a major reason why new cars don’t come with dipsticks. That’s not to say these transmissions are completely immune to leaks, but they are less likely to occur frequently.

Proponents of the idea also claim that by removing the dipstick from the transmission you will prevent the transmission from accumulating dust and moisture during overly frequent checks. Granted, this argument could apply just as much to an unkempt service center as it does to a modest driveway. Something that seems more compelling is how, by removing the dipstick, manufacturers save a few cents on the production line. It may seem like corporate greed, but for mass market items, those pennies add a lot of extra money to the bank.

Leaving out dipsticks may not sit well with people who like to work on their cars. While it may mean more dealer visits, the sealed transmission (as it’s commonly called) isn’t necessarily anti-DIY – provided you have the right diagnostic equipment and the knowledge to use it properly.

If there is no traditional dipstick, service technicians use an OBD scanner to diagnose the car’s fluid level. This happens after the engine and transmission have been running so that the fluid reaches a certain temperature range. At this time, the check plug is removed to inspect the fluid for viscosity, contamination and discoloration. A small drop is ideal, but anything where the liquid overflows – or doesn’t flow at all – requires corrective action. In the latter case, topping up via the filler plug is necessary, which is often done using a specialized pump.

The advancement of modern transmissions has helped eliminate the need for dipsticks, with sensors and software constantly communicating with the vehicle’s ECU to keep everything under control. The fluids themselves have also come a long way, as advanced synthetic fluids can tolerate higher temperatures while offering improved oxidation and wear resistance. This translates into longer life, as evidenced by the fluids in most modern transmissions lasting more than 100,000 miles without any problems.

Automakers obviously take this as an excuse to market them as durable for the life of the transmission. In business parlance, that is until the vehicle’s warranty is void. There is no such thing as a lifetime transmission fluid as they will deteriorate and break down just like any automatic transmission fluid. No matter what the car manufacturers say, transmission manufacturers often recommend regular fluid changes, even though you can still travel thousands of miles without needing to.