adverb taking the 'to' particle
Mimetic word for a high-pitched, repetitive squeaking or squealing sound, such as an engine belt slipping, skis on snow, or a tight hinge.
スキーが雪の上でキュルキュルと鳴った。
The skis squeaked on the snow.
エンジンからキュルキュルという音がする。
There's a squealing sound coming from the engine.