A dark ring on the concrete under a tractor appears overnight, and most drivers learn to step around it. Inspectors don't step around it. The citation for it is 49 CFR 396.5(b), "Oil and/or grease leak," and it shows up far more often than its low profile suggests. VioCodes records 204,701 violations of this code across 191,510 inspections, which means it is a routine finding, not an edge case.
If you want the code-level detail in one place, the violation page for 396.5(b) lists the fields I pull from. This post is about how to read the leak itself.
What the code is about
Section 396.5 sits in Part 396, the inspection, repair, and maintenance rules. Subsection (b) is the leakage provision. The rule's purpose is simple: a vehicle should not be running with oil or grease escaping from it in a way that shows the equipment is not being kept in proper condition. Because the exact wording is what an inspector works from, read the current text on eCFR rather than relying on my paraphrase: 49 CFR 396.5 on eCFR.
How inspectors read a leak
Inspectors are looking at three things:
- Is it active? Wet, fresh fluid is a live leak. A dry, caked film with road grime stuck to it tells a different story, though it still gets noticed.
- Where is it coming from? Common sources include rear main and front engine seals, the differential pinion and axle seals, transmission and power steering lines, and wheel-end seals. A wheel-end seal leak often shows up as a dark streak on the inside of the rim or down the face of the brake drum, not as a puddle.
- Does it point to a failing part? A slow weep at a gasket may be an acceptable finding to record. A stream from a seal that is clearly failing is a repair order waiting to be written.
The question is rarely whether there is any oil on the truck. It is whether there is an active leak and what component it points to.
Why this code carries weight
In VioCodes' data, 396.5(b) has a severity weight of 3 and belongs to the Vehicle Maintenance BASIC. The code is not flagged as an out-of-service indicator (oosIndicator is false), so a citation alone is not an automatic shutdown. That said, 1,066 violation records for this code are marked out of service in the data, so an inspector can and does take a vehicle out of service for it. What separates the two outcomes is what the inspector finds at the time, not the code number.
The scoring side matters too. The calculator applies time weights to violations based on how recent they are:
| Age of violation | Time weight | |---|---| | 0–6 months | 3 | | 6–12 months | 2 | | 12–24 months | 1 | | More than 24 months | 0 |
Those weights mean a leak citation from last spring counts for more than one from two years ago, and it decays to nothing after 24 months. The calculator also caps severity contribution at 30 per inspection per BASIC, so a single bad inspection cannot push that BASIC's score without limit. Repeated leak findings across several inspections, though, add up.
If you are new to terms like BASIC or severity weight, the glossary defines them.
What actually fixes it
Cleaning a leak without repairing it does not solve anything. The fluid comes back, and the next inspector sees a fresh trail where the old one was. A few practices make the difference:
- Look underneath during the pre-trip. Check the drive axles, the wheel ends, and the engine pan, not just the tires and lights. Ask whether anything is wet, not only whether it is dripping.
- Write it down. A driver defect report with the location and severity, followed by a dated repair order, is what proves the leak was found and addressed.
- Track repeat units. If the same tractor keeps showing leaks, the problem is usually the maintenance interval, not bad luck. Check seal and gasket replacement practices on that unit.
- Fix the seal, not just the symptom. Tightening a fitting can stop a weep, but a failing seal usually needs replacing before it fails completely.
Key takeaways
- 396.5(b) is a common Vehicle Maintenance finding: 204,701 violations across 191,510 inspections in VioCodes data.
- It has a severity weight of 3 and is not flagged as an out-of-service indicator, but 1,066 recorded violations are marked out of service.
- Recent citations count more in the calculator: time weights run 3, 2, 1, then 0 across the 0–6, 6–12, 12–24, and over-24-month windows.
- Inspectors look at whether a leak is active and which component it points to, not just whether oil is present.
- Document each leak with a defect report and a repair order, and watch for units that keep coming back.
Once you know which of your units keep leaking, run the numbers on how those citations age into your scores with the calculator.