Need help with textures

I’m trying to use texture mapping to color this motor model I’ve made but when I add the texture, the ROBLOX default metal texture disappears. Is there a way to add both my texture which only has colors and also have the lines and stuff that the default metal texture has?

I’m really new to texturing so I have no idea if what I’m asking is possible.

The only solution I found was to export each part with different colors separately and group them. Although, this is extremely inefficient because these models will be moving constantly throughout the game and if I do this with every single model, I’m assuming it would cause unbearable lag.

Is there a way to have the model as one mesh part and color it while keeping ROBLOX’s default textures or somehow adding them onto my texture map so that they line up?

(I’m using blender)

with texture map
motor_with_texture.PNG

without textures
motor_without_texture.PNG