What are the signs of water ingress in a manual transmission?

[Nolan]

"Mild water ingress in the transmission: Signs include partial rusting of screws inside the transmission. Moderate water ingress: Signs include a white emulsion-like substance adhering to the oil pan. Severe water ingress: Signs include slipping, shaking, and gear shifting hesitation. Mild water ingress in the transmission: In such cases, it is necessary to replace components like gaskets, oil seals, and friction plates. Moderate water ingress in the transmission: If there is excessive standing water on the road and splashing waves hit the car body, it generally leads to moderate water ingress in the transmission. In such cases, it is necessary to completely replace components like gaskets, oil seals, and friction plates, as well as the automatic transmission fluid and differential. If components like the automatic transmission multifunction switch have been exposed to water, they must also be replaced. Severe water ingress in the transmission: If a significant amount of water has entered, the color and viscosity of the oil-water mixture can be observed to determine the severity. For transmissions with severe water ingress, many components need to be replaced, including rubber-based elements like gaskets and oil seals; friction plates must be replaced because they consist of steel plates and high-density wood-resin materials, which swell when exposed to water and affect friction performance. The transmission fluid and differential oil must also be completely replaced. In cases of severe water ingress, the chain sprocket may need to be replaced. Whether to replace the transmission valve body depends on the situation, as water ingress reduces lubrication effectiveness. If components like the automatic transmission multifunction switch have been exposed to water, they must also be replaced."