Engine oil is the lifeblood of your motor, yet the wall of bottles at the parts store confuses most drivers. Here is how to choose with confidence.

Read your owner’s manual first

The manufacturer lists the exact viscosity grade and specification your engine needs. Using the wrong grade can reduce fuel economy and even void your warranty.

Understand the viscosity numbers

In a grade like 5W-30, the number before the W is the cold-flow rating (lower is better in winter) and the second number is how thick the oil stays when hot. Match these to your climate and engine.

Synthetic vs conventional

Full synthetic oils flow better when cold, resist breakdown at high temperatures and last longer between changes. They cost more but are worth it for modern turbocharged engines.

Check the specifications

Look for API (SP, SN) and ACEA ratings, and any manufacturer approval such as VW 504 00 or Dexos. Steve AutoParts carries a full range of certified oils and filters.