I repair old motorcycles. The meter’s mechanism creaks but can't be disassembled. I need a cleaner-lubricant that works without it. Moisture may cause rust, narrowing clearance. I seek a durable lube with rust prevention.

As you guessed, the cause of the squeaking noise is
As you guessed, there is a possibility that the clearance is narrowing due to rusting caused by moisture and condensation.
Therefore, you are looking for a product that has both lubricating and penetrating properties.
The following products are considered suitable among our products.

LS Bellhammer undiluted solution (long life, smooth lubrication, high permeability)
Characteristics: Highly penetrating, gradually penetrates into tight crevices.
Recommended use: Ideal for eliminating mild squeaking noises and maintaining smooth operation for a long time.

Suggested Use.
For best results, use LS Bellhammer undiluted solution.
Allow some time after application to allow the product to penetrate into crevices.
It is recommended to try a small amount at first, and adjust the amount as you see fit.
We do not know the details of the use environment and condition of the product, so please make your judgment while checking the actual situation of the product.