My old 1985 BMW has an oil level sensor. It made lika a small cylinder or canister with a wiring connector on top. There are contacts inside, and a ball float to operate the contacts. The sensor extends into the oil pan, and has only a small hole to allow oil inside the canister to move the float in...

Every day we see hundreds of big trucks on the road going in opposite directions. You just know that many of them are hauling the same cargo - one hauling it out of an area, and another hauling it into the same area. (In my area, every time I see a truck load of coal heading north passing another he...