How our verdicts work
Every engine in the database gets a single, honest verdict on a 7-tier scale — backed by a four-pass research process. Here's exactly what each verdict means and how we get there.
The 7-tier verdict scale
We deliberately separate a bad engine from one that's just risky to buy blind. A tough diesel can be excellent with the right history and a poor gamble without it — those are different verdicts.
No significant known issues. Trusted at high mileage. Buy with confidence if the service history is reasonable.
Minor issues only, easy to maintain, no design flaws. A safe used buy.
Fine if serviced correctly — but it punishes neglect hard. History and the right consumables matter.
The engine itself is OK; condition is everything. Unknown or patchy history = walk away.
Won't fail catastrophically, but when things do go wrong the repairs cost a lot. Budget accordingly.
Known design issues and recurring faults that were never fully resolved. Buy only with eyes open.
A design flaw with no reliable fix, or a catastrophic-failure risk. Not worth the gamble at any price.
The 4-pass research method
No engine is marked done until all four passes are complete. The goal of each entry is to answer one question:
"What would make someone regret buying this car that isn't already on the page?"
General baseline
A broad reliability search per engine to establish the common picture. Treated as a starting point only — generic results rarely surface the real quirks.
Adversarial forum dig
Owner forums and worst-case searches ("catastrophic", "avoid", "write-off"). This is where the failures that dealers don't mention show up.
Isolated per-variant check
Every engine variant is researched on its own. We never bundle siblings (e.g. 2.4 + 2.5 + 2.8), because averaging them hides variant-specific faults.
Per-issue deep-dive
For each issue found: how critical is it, is there a workaround (redesigned part after year X, remap, EGR delete), what does the fix cost, and what happens if it's ignored?
What every engine page gives you
- ✓A plain-language verdict and the reason behind it
- ✓Specific known issues, with severity and typical onset mileage
- ✓Documented fixes or workarounds, and rough repair cost
- ✓Year cutoffs where a fault was fixed in production
- ✓Fault codes worth scanning before you buy
- ✓A pre-purchase checklist to run next to the car
Verdicts reflect documented, community-sourced patterns — not a guarantee about any individual car. Always combine this with an in-person inspection. See our disclaimer.