What weight of oil is used in a 78 ford f100 ranger?

The weight of oil used in a 1978 Ford F-100 Ranger depends entirely on the engine it has. Ford offered several different engines for that year and model. You must check your owner's manual or a sticker under the hood to determine the correct engine.

Once you know the engine, you can find the recommended oil weight and capacity in the owner's manual or online resources like a repair manual for that specific year, model, and engine. The oil weight will likely be specified as something like 10W-30, 10W-40, or 20W-40. The capacity will be given in quarts (or liters).