Eli5 How come auto repair garages don’t keep spare car parts on site and have to order them?



I’d understand them not keeping spares of larger parts at the garages due to space issues, but I’m confused they wouldn’t have something like spare O-rings around (one is stopping my car from getting fixed/tested and the garage told me there’s been a shipping delay).

In: Engineering

I’m an electrician. I have hundreds of breakers at my shop. Still buy breakers all the time. There’s just SO MANY types and sizes.

They keep some, but the problem is that there’s so many different parts for different models from different years that keeping everything on site is impossible. It just ends up being easier to order parts as needed in many cases.

They do carry some parts, financially it wouldn’t be the best buisness model for them to carry everything that could go wrong with a vehicle. Most mechanic shops have parts stores that have everything (mostly) on speed dial that deliver them parts all day long.

It costs money to buy spare parts you don’t necessarily need… and it takes space from the storage areas that can be used for other things that are of more immediate need, which is more use of money unnecessarily. Just my thought but I may be wrong.

There are lots of different types of cars from lots of different manufacturers, and each one uses different parts. Most garages probably have dozens of different o rings in stock, but that only does so much good when you come across a car that needs some weird size of o ring, made out of some sort of oddball material. It’s just not feasible to keep spares of every single car part ever used stock.

There are parts that most garages will keep stock of, like serpentine belts. Those are generalized enough across manufacturers that it’s sensible to keep a few in stock.

That’s often not the case with more specialized parts especially critical ones like o-rings. A BMW o-ring might be different from a Subaru o-ring, and it’s easier to just order the part when needed than try to build an inventory that you may or may not use.

I know your frustration. My car once sat for two weeks waiting for O-rings because those particular O-rings are made of a special material, viton, and you can’t just use any old O-ring. I have an O-ring assortment kit in my shop, but I regularly have to go get a different one because the particular thickness is not in the kit.

[What an O-ring assortment looks like](https://newcontent.westmarine.com/content/images/catalog/1500/20216602_1500.02022021090008.jpg)

The local garage I use orders them from suppliers like Napa, who can deliver same/next day from a regional warehouse. Like a van shows up 2-3 times a day with parts he’s ordered for the cars he’s working on.

On average a single car has 30,000 parts. There are nearly 1,000 car models available on the road. That’s roughly 30 million parts that need to be bought, kept track of and inventory and also stored. How would you think that’s possible?

* There is a large network of auto parts specifically for repair shops.
* They can get most parts the same or next day.
* It’s actually pretty rare for a repair shop to have to wait longer than that for parts to arrive.
* The parts network has the space to store a huge amount of parts while the repair shop doesn’t.