Recommended oil for a 1999 ford F-150 pickup truck?

The recommended oil for a 1999 Ford F-150 depends on the engine it has and the climate you live in. Ford used several engines in that year. To be certain, check your owner's manual. It will specify the correct oil viscosity (like 5W-30 or 10W-30) and API certification (like SL or SJ).

However, as a general guideline, for most 1999 Ford F-150s and assuming your owner's manual is unavailable:

* 5W-30 is a common and often recommended viscosity for a wide range of temperatures. It's a good all-around choice.

* 10W-30 is another suitable option, particularly in warmer climates.

Regarding API certification: Look for an oil that meets or exceeds the API certification specified in your owner's manual. Older certifications like SJ or SL are common for this model year, but newer certifications (SM, SN, SP, etc.) will generally be backward compatible and offer improved performance.

In short: Consult your owner's manual for the definitive answer. If you can't find it, 5W-30 is a safe bet for most conditions, but always prioritize the information in your owner's manual.