What type of motor oil should is used for a 1991 Chevy caprice?

The 1991 Chevy Caprice's recommended oil type depends on the engine it has. There were several engine options available that year. You'll need to check your owner's manual or the sticker under the hood (often near the radiator or oil filler cap) to determine the specific engine. However, generally speaking:

* Most likely, it will call for a conventional 10W-30 oil. This was common for that era.

* If the engine is particularly worn, a 20W-40 might be recommended. This is thicker and offers better protection for higher mileage engines.

* Modern, multi-viscosity oils (like 5W-30 or 10W-40) are generally acceptable substitutes, provided they meet the API specifications (discussed below). These often offer better performance and fuel economy.

Crucially, check the API rating. The owner's manual or underhood sticker will specify an API service designation (e.g., SF, SG, SH, SJ). Modern oils often exceed these older standards, but you want to ensure the oil at least meets the minimum standard for your engine. Using an oil with a higher API rating is generally fine.

In short: Start by identifying your engine type. Then, look for the recommended oil viscosity (like 10W-30) and API service rating in your owner's manual or underhood sticker. If you can't find this information, take your car to an auto parts store and they can help identify the correct oil based on your engine.