Maintenance Guide · Mobile Diagnostics · Hill Country TX
Maintenance intervals are real engineering — and the service-counter menu that halves them is real marketing. Every page below gives the honest manufacturer interval for Texas heat and dust, what the fluid or part looks like when it's genuinely done, how the job gets oversold, and the measurement that beats the calendar.
Two numbers in, a per-service verdict out. Runs entirely in your browser — your odometer reading is nobody's business but yours.
Digits only — 47,500, 120000, whatever it says today.
Age in years. Some fluids run on a clock, not a trip meter — leave blank to skip the time checks.
Enter miles or years first — the checker needs one real number.
Every 5k–10k mi / 1 yr
Modern full-synthetic oil in a modern engine is engineered for 7,500–10,000 miles or a year, and most manufacturers say so in the owner's manual. The 3,000-mile sticker on your windshield was written by an oil industry, not a metallurgy department. But 'modern interval' assumes modern driving — and stop-and-go Hill Country traffic, summer under-hood heat, towing, and unpaved dust roads are what every manual calls severe service, which cuts the interval roughly in half.
The inspection that beats the calendar
Every 5k–8k mi
Front-drive cars chew the outside shoulders of front tires while the rears barely wear. Rotate every 5,000–8,000 miles and a set lasts its full tread life; skip it and you replace two tires where the pattern called for none. The oversell is not the rotation itself — it is what gets attached to it.
The inspection that beats the calendar
Every 2 yr / 30k mi
Brake fluid is hygroscopic: it pulls water out of the air through the system, year after year, and water lowers the boiling point and rusts calipers and ABS modules from the inside. A 2-year/30,000-mile interval is a legitimate engineering answer for humid climates. It becomes an upsell only when nobody ever MEASURES the fluid in YOUR brakes.
The inspection that beats the calendar
Every 4–5 yr / 30k–100k mi
Engine coolant does two jobs — freeze/boil protection and corrosion inhibition — and the additives that do the second one wear out on a schedule. That is real. What is not real is the $250 machine power flush every shop wants at 30,000 miles when many modern OEM extended-life coolants are good to 100,000 miles or five years, and mixing incompatible chemistries does more damage than stretching a flush interval ever did.
The inspection that beats the calendar
30k–100k mi (or lifetime)
Every flush-vs-change argument on the internet is two halves of the truth shouting. Fluid does degrade and friction material does accumulate — a service interval exists for a reason. But forcing a machine through a 150,000-mile transmission that has been fine can dislodge the varnish the valves are currently living on. The diagnostician's answer is neither camp: measure the fluid, check the pan for what the magnet says, and service the way the manufacturer's procedure specifies — which is almost never attach a pressure machine.
The inspection that beats the calendar
Every 30k–100k mi
A copper plug at 30,000 miles is an engineering fact; a double-platinum or iridium plug due at 100,000 miles that reads like new at 60,000 is also an engineering fact. Plugs are cheap evidence machines: pull one and its color and electrode condition tell you about fuel mixture, oil burning, and detonation — information nobody selling you a tune-up bundle wants you to have.
The inspection that beats the calendar
Every 15k–30k mi
Dusty Texas Hill Country roads and pollen season make filter replacement real maintenance, not a scam — a loaded filter genuinely costs you airflow. The problem is never the part; it is that a dirty filter becomes the free-inspection headline at every lube shop because it converts into the bundle that follows it.
The inspection that beats the calendar
Every 15k–30k mi / yearly
It exists, it works, and in pollen country it deserves replacing — but it is the one maintenance item where paying a shop $90 for a five-minute job is purely financing their rent. The filter costs less than a lunch, sits behind one glovebox, and requires zero tools.
The inspection that beats the calendar
Inspect 60k, replace 90–105k
A glazed, cracking belt at 90,000 miles is due — that is real. But the belt that squeals at startup on a 60,000-mile car is usually telling you about a failing tensioner, a dragging idler, or an AC compressor bearing, and replacing the belt alone buys silence until everything else chews through the new one. The belt is often the victim, not the culprit.
The inspection that beats the calendar
Every 3–5 yr in TX heat
Under-hood temperatures are battery killers — sustained heat accelerates plate corrosion and water loss, which is why Hill Country cars earn replacement far more often than northern ones. The oversell is not the battery: it is every battery that gets replaced while whatever actually drained it keeps draining, at your expense, all week.
The inspection that beats the calendar
No interval. Evidence only.
There is one legitimate fuel-injector cleaning: the one prescribed by an actual measured fault — a flow-balance test or fuel-trim evidence naming a dirty or stuck injector. Everything else on the menu — the $140 top-tank cleaner added to every oil change, the walnut-media induction service sold on mileage to a port-injected car that cannot benefit from it — is revenue dressed as maintenance.
The inspection that beats the calendar
Only if hydraulic — inspect
Electric power steering has no pump, no fluid, no lines — which means the flush that lives on every maintenance menu is a service for a component an increasing share of cars do not own. If your car does have hydraulic steering and it is on original fluid at 120,000 miles, a drain-and-fill may genuinely help a groaning pump. It should never be a surprise line item on a car that is 40,000 miles in.
The inspection that beats the calendar
Intervals on this page are manufacturer schedules and honest street pricing for independent shops, published as a benchmark — not a quote for your car. The line item nobody else prices: whether YOUR car is actually due. A flat $150 diagnostic answers that with evidence instead of a calendar. An interval is a risk budget, not a law: it is the mileage at which the manufacturer stops guaranteeing the part isn't degraded — not proof that it is. The only number that beats a calendar is a measurement, and every page here names the one that fits the job.
Staring at a printed service menu? Scan it for red flags in your browser, price any real repair in the repair cost guide, or book the evidence-based version: