A. A full-synthetic heavy-duty engine oil typically is offered in a 5W-40 or 5W-30 grade.
The advantages of 5W-40 or 5W-30 full-synthetic oil include:
• Wider temperature range performance, ranging as low as -20 degrees F or lower to the same or higher temperature operating ranges. In contrast, a 15W-40 is typically only rated down to +15 degrees F on average.
• Improved fuel economy versus a 15W-40 oil, typically up to 3%.
• Reduced dependency on cold weather block heaters and potentially dangerous starting aids.
• Best opportunity to consolidate engines oils in mixed gasoline and diesel engine fleets.
• Engine oil service interval optimization. When combined with an oil analysis program, full-synthetic oils are very robust and tend to promote longer service life versus conventional oils.
There are a few full synthetic 15W-40 oils on the market, but in most cases, the investment in a full synthetic demands getting the full advantages versus a 15W-40 type heavy-duty engine oil.