How to know when your Transmission needs Maintenance
Transmissions require maintenance at regular intervals. If you are experiencing symptoms, it is likely more than maintenance that you need.
Most automatic transmissions are expected to last 30,000 miles between fluid changes, but 15,000-mile intervals are more prudent for the typical driver. Manual transmissions are more forgiving, and often have longer service intervals, say about 60,000 miles, depending on make and model. Also, most Front Wheel Drive automatic transaxles no longer have serviceable filters, so maintenance is just a fluid change.
As for those symptoms: With most older automatic transmissions, slight RPM increases between gears can be a signal that more fluid is needed. Often times, however, it can be too late. If any symptoms appear, damage may already be done. Adding fluid may help the symptom for now, but clutch and brake elements receive extra wear while trying to engage with low fluid in the transmission.
Transmission fluid also breaks down over time. The automatic transmission produces a tremendous amount of heat, mainly in the torque converter. If the fluid is not changed regularly enough, the fluid will break down from the heat.
Overheated fluid can also boil, meaning there will be air in the fluid channels, which will cause the actuators (clutches and brakes) to be unable to fully engage. This could be a symptom that the transmission needs service, but again, if the heat buildup is this bad, something else is wrong.
Manual transmissions also require service, but most use a different type of fluid. Typical manual transmission use gear oil, which is a heavy lubricant designed to withstand high pressure between gear contact surfaces. These transmissions do not have fluid pumps or actuators and do not produce as much heat; therefore they often have longer service intervals and are more forgiving of a lack of service.
Some newer manual transmissions use automatic transmission fluid, and many are now using more exotic lubricants, which must be obtained at the car dealer. They do have service intervals. Just like an automatic transmission, you are best advised to service the transmission at regular intervals. With a manual transmission, if you hear or feel a problem with any gear, there is likely damage already done. Just be careful to remember that the clutch may be the problem with a manual transmission.
The bottom line is that if you want your transmission to take care of you, take care to service it at regular intervals. If you notice symptoms appearing you may very well have actual problems already.
