For most of my life I've done my own repairs and maintenance. A few years ago I was involved in a multi car pile up with injuries, was sued for $525,000 and was deposed before the case went to arbitration.
Many of the questions the lawyers asked were related to maintenance....things like when was the last time my tires were rotated and balanced, brakes replaced, were the rotors turned.... etc.
Now, I take both my truck and trailer in for service, have it noted on the receipt for future reference and keep each and every receipt.
180 seems quite high though, or roughly two hours labor at $90 per hour...which is what the diesel shop charges for labor.... maybe you should look for another mechanic and inquire about the cost before having the job done?
For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.