What type of oil should you use in your 1989 wrangler 2.5 four cylinder?

The 1989 Jeep Wrangler 2.5L four-cylinder engine calls for a conventional 10W-30 motor oil. However, you should always check your owner's manual for the manufacturer's specific recommendation. While 10W-30 is common, they might specify a certain API rating (like SG, SH, or SJ - older specs) or even a specific brand. Using a higher quality oil (like a high mileage formula) won't hurt and might even be beneficial given the age of the engine. Never use anything significantly different without consulting your manual.