The 2.9L Cologne V6 takes about 4.5 quarts of 10W-30 with a Motorcraft FL-1A filter — a 30-minute service that you should run every 3,000 miles if the truck sees trail duty.
The 2.9L Cologne V6 (1986–1990 Bronco II) and the earlier 2.8L share a similar service procedure. Both engines benefit from short oil intervals — these are pushrod, hydraulic-lifter V6s with timing-driven oil pumps, and they don't suffer fools when it comes to dirty oil. Cracked-head failures are partly attributed to chronic overheating from neglected cooling, but tired oil compounds the problem by letting the bearings load up under heat. Don't stretch the interval to "5,000 to be safe." Run it at 3,000 miles for trail trucks and 4,000 for street-only.
Use a conventional 10W-30 — Valvoline, Castrol, or Pennzoil are all fine. Synthetic is allowed but offers no real benefit on an engine of this design and age. The Motorcraft FL-1A is the OEM filter and is still in production; aftermarket equivalents include Wix 51515, Fram PH16, and K&N HP-1017. The 1A is roughly $8 at any parts counter and there is no reason to buy anything more exotic.
Park on a level surface. Run the engine to operating temp for about five minutes — warm oil drains faster and carries more contaminants out with it. Shut off, raise the front on a jack and set stands under the frame rails behind the radius arm mounts. The drain plug is on the bottom-rear of the oil pan, takes a 15mm socket, and torques to 15–22 ft-lbs against a new crush washer. The filter sits on the driver side of the block — spin it off by hand or with a strap wrench, wipe the mounting surface clean, prime the new filter with a splash of oil, and hand-tighten three-quarters of a turn past gasket contact.
Refill with 4.5 quarts, run the engine for 30 seconds, shut down, and check the dipstick after a one-minute settle. Top to the upper hash. Inspect the drain plug and filter for seeps before you put the truck back on the ground.
| Part | Vendor | Est. price |
|---|---|---|
| Motorcraft FL-1A oil filter | Motorcraft / Amazon | ~$8 |
| 5 qt Valvoline 10W-30 conventional | Walmart / Amazon | ~$22 |
| Drain plug crush washer | Dorman 65275 | ~$4 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.