If you're about to buy a Caterpillar 315 excavator—new or used—this checklist is for you. It is based on eight years of managing heavy equipment budgets at a 170-person construction company, and more than a few expensive mistakes I'd rather not repeat.
Look, the Cat 315 is a great machine. Here's the thing: it's also easy to overbuy, overpay, and under-plan. This checklist has five steps. Do them in order. Skip one, and you'll probably explain it to your accountant later.
Step 1: Define the Job Before You Define the Machine
You're not buying a 315. You're buying a set of outcomes: digging, loading, grading, demolition. The attachment package and stick length matter more than the paint color.
In our operation, the 315 loads a slate truck at the top of a quarry for four hours a day. If we had bought a smaller excavator, we'd have needed two extra cycles per truck. That would have cost us roughly $18,000 per year in extra fuel and operator hours. So the 315 was the right size—not because it was the newest model, but because the cost per ton of material was lower.
Write down what the machine will do. Be specific:
- How many hours per month will it run?
- Who will operate it? One person or a rotating crew?
- What attachments are required? A thumb, quick coupler, hydraulic breaker?
- Will it sit on a trailer for travel, or live on one site?
If you can't answer those four questions, you're not ready to talk price.
Step 2: Calculate Total Cost, Not the Sticker
When we bought our first 315 in 2021, I compared two dealer quotes. One was $146,000. The other was $134,000. I almost signed the second one until I ran the full cost line.
The cheaper quote didn't include a hydraulic thumb, a rear camera, or dealer setup. Add those in, and it came to $149,700. The first quote included everything, plus one scheduled 500-hour service. The difference was about $3,300 in the first year, which is nothing compared to the cost of buying the wrong configuration.
Here's what I put into every machine purchase now:
- Base price and any rebates
- Attachment package and installation
- Delivery: lowboy, trailer, or a slate truck? Include permits and escort vehicles
- Insurance and property tax
- Dealer prep and inspection
- First-year service package
- Projected resale value after five years
We collect dealer quotes every time, and I track them in a spreadsheet. Not because I love spreadsheets, but because I got burned twice on hidden fees. Once I assumed "prepared for work" meant "with attachments." That mistake cost us $4,800. I don't assume anymore.
Step 3: Vet the Dealership, Not Just the Map
Typing "Caterpillar parts dealer near me" into Google is a fine first step. It's not a fine last step. Proximity is not the same as support.
In 2023, I searched that exact phrase and picked the closest dealer—18 miles away. They didn't have a $40 hydraulic filter in stock. A dealer 52 miles away had it and delivered it the same afternoon. The "closer" dealer cost us two full days of downtime. I still use the phrase, but now I use it to build a list, not make a decision.
Ask each dealer three questions before you buy:
- Do you stock undercarriage parts for the 315 in your local warehouse? Stocking matters more than inventory on a website.
- Do you have a delivery truck? We've cut our parts turnaround from five days to two when a dealer can bring parts to the job site.
- Can you support a 9 PM breakdown? Our second shift once blew a hydraulic line at 9 PM. The dealer who answered the phone got our next machine order. Simple.
One more note: when you walk into a dealer's store, ignore the swag. A branded bucket hat and a coffee mug are nice, but they are not line items. Last year I watched a colleague negotiate hard and then accept a 12% markup on filters because the salesman was "a good guy." The bucket hat was free. The markup wasn't.
Step 4: Audit the Service History Like You Audit Invoices
Used Cat 315s are everywhere. Low hours are attractive. But low hours don't equal low wear if previous operators didn't follow service intervals.
Low hours don't equal low wear. You're buying the maintenance history, not the story.
I once compared two identical 315s side by side—same year, similar hours, similar price. One had oil analysis reports, grease logs, and a folder of receipts. The other had a single purchase order and a story. Guess which one needed a $14,000 undercarriage within six months? The one with no paperwork.
When you're looking at a used machine:
- Ask for oil sample reports from the last three changes. If they don't exist, assume the oil wasn't tested.
- Ask for undercarriage wear measurements. A new set of tracks can cost more than a down payment.
- Ask how many operators ran it. Rental fleet machines are touched by everyone and maintained by no one.
- Ask for the machine's telematics data. If the seller won't share it, ask yourself why.
What I mean is: you're not just buying hours. You're buying the maintenance culture behind those hours.
Step 5: Lock Service and Parts Pricing Up Front
The machine is the easiest part of the negotiation. The service agreement is where the money goes.
After we bought our second Cat 315 in November 2024, we negotiated a one-year fixed-rate service plan: scheduled fluid and filter changes, a 10% parts discount, and no portal fees for online ordering. That might sound small. But it replaced the old process of calling around and waiting on quotes, and it cut our parts order time from about 45 minutes down to 10.
Efficiency in procurement is a competitive advantage. The less time your team spends chasing parts, the more time they spend making money. Our routine maintenance parts are now ordered online, and automated reminders mean we no longer "discover" a missed service interval at 2 PM on a Friday.
When you compare service plans, make sure each quote includes the same items:
- Fluids and filters
- Travel time for mobile service
- Diagnostic fees
- Shop labor rate
- Emergency parts delivery
As of January 2025, our dealer's hourly labor rate is $198. That's not a bad rate if the dealer is competent. It's a terrible rate if you pay a mechanic to wait on a part that was never stocked.
What Most Buyers Miss
Here are three things I've learned the expensive way.
1. Free stuff is never free
Every time a salesman hands me a bucket hat, I check my purchase order. I'm not saying they're trying to distract you. I'm saying a lot of money gets spent in the five minutes after a handshake. Stay focused on the written line items.
2. Don't turn electrical repairs into a surprise project
Last year, our site air compressor's pressure switch died. My mechanic said, "I can fix it." He searched "how to wire air compressor pressure switch", watched one video, and rewired it. Three blown fuses later, the motor was dead. The replacement compressor cost $1,100. An authorized repair would have cost $350.
If you don't know the machine, don't learn on the machine. A wiring harness on a Cat 315 is not a phone charger. Use a qualified electrician, even if it's "just a switch."
3. Budget transport like it's a line item, not an afterthought
If the machine has to travel, the cost is more than fuel. Permits, escort vehicles, site access, and the risk of damage all add up. We once moved a 315 using a slate truck and trailer combination that was barely legal. It made it, but the permit and inspection fees were $900 I hadn't planned on.
Final Thought
A Caterpillar 315 can be one of the best investments you make—if you buy it with a plan. This checklist doesn't guarantee that nothing will break. It guarantees that you'll see the cost coming sooner. That's the closest thing to control we get in this business.
That's it. Five steps. Do them in order.
