Why does the car feel sluggish when starting after changing the transmission fluid?
3 Answers
The reasons for feeling sluggish when starting after changing the transmission fluid are: 1. Overfilling of transmission fluid, i.e., exceeding the dipstick line. When the car starts, the gears have to overcome the resistance of the excess fluid, which consumes power; 2. The agitation of the gears causes the fluid to foam, introducing air into the oil circuit that reaches the clutch. When shifting to D gear, the presence of air between the clutch plates prevents them from pressing tightly, causing clutch slippage, making the car unable to move, and accelerating clutch wear. Transmission fluid is a lubricant that keeps the gear system clean, ensuring the transmission works properly and extending the lifespan of the transmission components.
I just had my transmission fluid changed at my friend's repair shop last week, and now the car feels sluggish when starting, like stepping on cotton. The mechanic told me that this is most likely due to overfilling the fluid—if the fluid level is too high, it can create foam and affect hydraulic pressure. Another possibility is using incompatible fluid. My car has an 8AT transmission, and if CVT-specific fluid with the wrong viscosity was used, the clutch plates inside could slip. They might also have skipped the fluid pressure reset procedure during the change, which can cause delayed shifting, making the car feel like an old ox pulling a cart. By the way, have you checked the oil pan filter? If the old filter wasn't replaced, debris could clog the fluid passages, leading to this issue. In severe cases, the transmission might even overheat and trigger a warning.
Last month, after changing the transmission fluid in my old Accord, it noticeably became sluggish when starting. I took it to the 4S shop for inspection, and they found two issues: first, the mechanic forgot to reset the transmission adaptive program, so the car's computer was still remembering the friction coefficient of the old fluid; second, the oil pan gasket was aging and leaking, causing nearly half a liter of new fluid to leak within an hour. The technician used a diagnostic tool to rematch the clutch pressure and replaced the gasket, after which the car immediately regained its power. I suggest you first check the transmission dipstick—the fluid level should be between the upper and lower marks when the engine is cold. If the fluid level is normal, it’s likely that you’ll need to visit the 4S shop to have the shift logic relearned using specialized equipment, especially since turbocharged cars are more sensitive to this.
