The Opel AF40 is the GM badged Aisin TF-80SC six speed torque converter automatic (Insignia A, Astra H/J, Zafira B/C and others). If the gearbox oil (ATF) is changed, it keeps working for a long time.
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With neglected oil: a harsh N to D engagement, jerking on downshifts, and delayed lock-up. Burnt ATF loses its lubricating and friction properties, and deposits build up in the valve body. A simple drain leaves a lot of old oil in the torque converter, so the job is often a flush, not just a drain and refill.
Workshops recommend an oil change around 60,000 to 80,000 km. The "lifetime fill" promise does not replace that.
What to check
- Try it cold and warm: N to D and R engagement. A strong jolt is suspect
- Watch the downshifts when slowing: jerking, delay
- Ask when the last ATF change or flush was done: ask for the invoice