People often forget about the fluid in their hard-working transmission. While the fluid doesn't need to be changed as often as an engine, your transmission produces its share of shavings and gunk which the filter can handle for only so long. Age takes its toll on fluid too, diminishing it's ability to lubricate and protect. Many claim that it is dangerous to change fluid in an older transmission, but new fluid won't bring on failure; neglect does. Do yourself and your C4 a favor, and change the fluid and filter soon.
| Make | Model | Years |
| Ford | Bronco | 1966 - 1969 |
| Ford | F-100 | 1965 - 1969 |
| Ford | F-250 | 1965 - 1969 |
| Ford | F-350 | 1965 - 1969 |
| Ford | Falcon Sedan Delivery | 1965 |
| Ford | Ranchero | 1965 - 1969 |
