ENGINE OIL
This guide is general information, not a substitute for your owner’s manual or a qualified technician. Always confirm specs and fitment for your exact vehicle.
Start with the owner’s manual
Your manual lists three things to match: the viscosity grade (for example 0W-20 or 5W-30), any required specification or approval, and the oil capacity with filter. Using the specified oil matters for engine protection and can matter for warranty coverage.
Reading the viscosity grade
In a grade like 5W-30, the number before the “W” (winter) describes how the oil flows when cold; a lower number flows more easily at startup. The second number describes thickness at normal operating temperature. Use the grade your manufacturer specifies.
Specifications and approvals
Look for the industry ratings your manual calls for, such as the API service category and ILSAC standard shown on the bottle, or the manufacturer’s own approval (for example GM’s dexos approval or a European maker’s numbered spec). Many modern and turbocharged engines require a specific approval.
Conventional, synthetic blend and full synthetic
Conventional oil is refined from crude oil. Full synthetic oils are more highly engineered and generally hold up better to heat and resist breakdown. Synthetic blends sit in between. Many newer engines specify synthetic oil; if yours does, use it. If your manual allows either, synthetic is an option but meeting the specified grade and spec is what matters most.
How often to change it
Follow the interval in your maintenance schedule, using the shorter “severe” or “special conditions” interval if your driving fits. If your car has an oil-life monitor, follow it and reset it after each change. Ford caps its monitor at 12 months or 10,000 miles, and GM recommends an oil change at least once a year regardless of the monitor. See how to read your factory maintenance schedule.
Don’t forget the filter
Replace the oil filter with each oil change, using a filter listed for your engine. AutoForge lists OEM and aftermarket filters by fitment with links to their sources.
Check the level
Check the dipstick regularly (some cars use an electronic level display instead) and top up with the same oil if needed. Dispose of used oil and filters at a recycling point; many auto parts stores accept them.