Sounds like old mate has a bad blind spot there!
But I've struck the same thing in the past too; one small engine mech who worked in our family OPE business was much the same.
Brilliant at small engine, farm machinery and milking machine diagnostics and repairs. But treated his own gear like Poo, especially his car!
Sounds like one of the diary farmers near here. He will proudly tell you he's never had to change the oil on his ute, just needs topping up every so often! Mind you he drove 20km to our place with a flat tyre because he didn't have a jack! He also has a dislike for the native Blackwood trees along the gravel roads and found out the hard way that an 80hp John Deere front end loader doesn't like felling trees at high speed. He split the tractor between the engine and gearbox on the spot !!
