Three separate vehicle issues have forced Volkswagen to begin a series of large-scale recall campaigns affecting roughly 2.6 million cars worldwide.

The most significant of the recalls by volume impacts about 1.6-million VW, Skoda and Seat vehicles equipped with a seven-speed dual-clutch automatic transmission. VW says these vehicles need to have their standard-issue synthetic oil replaced with mineral oil, as use of the former can lead to “electronic malfunctions,” especially in hot and humid locales and in prolonged stop-and-go driving conditions.

Notably, the gearbox campaign involves 640,309 Chinese-market cars, making it VW’s largest-ever recall in China.

VW is also calling back 800,000 Tiguan SUVs – including 61,000 in the United States – to address an issue in which a melted fuse can cause a partial vehicle lighting failure. The defective Tigauns were built between 2008 and the middle of 2011, Volkswagen says.

Finally, the third recall involves 239,000 Amarok pickups that are at risk to develop fuel line leaks.