The Blazer typically uses conventional 5W-30 motor oil, with about 5 quarts needed for the 4.3L V6 and about 6 quarts for the 5.7L V8. In hotter climates, 10W-30 is acceptable, and synthetic oil can be used if you prefer. Always check the owner's manual or the under-hood label for the exact specification for your engine.
Engine options and oil viscosity
Below are the standard oil viscosity guidelines for the common engines in the 1998 Blazer, with notes for climate and oil type.
4.3L V6 engine
The majority of 1998 Blazers used the 4.3L V6. For this engine, use 5W-30 as the baseline. In hot or high-temperature climates, 10W-30 is acceptable.
- Viscosity: 5W-30 (baseline); 10W-30 in hot climates.
- Oil type: conventional mineral oil is standard.
- Oil for this engine should meet API service requirements appropriate for the era (e.g., SJ/SL or later).
- Using synthetic oil is optional; it does not require a different viscosity than recommended.
Note: Always verify the exact spec for your vehicle from the owner's manual or service sticker.
5.7L V8 engine
Some 1998 Blazers came with the 5.7L V8. The same viscosity guidance generally applies: 5W-30 as the baseline, with 10W-30 acceptable in hot climates.
- Viscosity: 5W-30 (baseline); 10W-30 in hot climates.
- Oil type: conventional mineral oil is standard; synthetic is optional.
- Ensure oil meets API service categories appropriate for the era.
As with the V6, always confirm the exact spec from the manual or under-hood label for your engine variant.
Oil capacity and change intervals
In addition to choosing the right oil, knowing how much to fill and how often to change it helps maintain engine health.
Capacity by engine
The 4.3L V6 typically holds about 5 quarts of oil with filter. The 5.7L V8 capacity is usually around 6 quarts with filter.
- 4.3L V6: approximately 5 quarts with filter.
- 5.7L V8: approximately 6 quarts with filter.
Always confirm capacity for your specific model and engine with the owner’s manual or a dealership if you’re unsure.
Change intervals
Oil-change intervals vary with oil type and driving. Conventional oil: typically every 3,000–5,000 miles. Synthetic oil: 5,000–7,500 miles under normal driving, though urban/city driving or severe service may shorten this.
- Conventional oil: 3,000–5,000 miles (roughly every 3–6 months).
- Synthetic oil: 5,000–7,500 miles (or as recommended by the oil brand).
Always follow the intervals recommended by your manual and consider driving conditions such as "severe service" that GM notes for older vehicles.
Summary
For a 1998 Chevy Blazer, the standard oil is conventional 5W-30, with 5 quarts for the 4.3L V6 and 6 quarts for the 5.7L V8. You can run 10W-30 in hot climates, and synthetic oil is optional. Verify exact specs on the owner’s manual or under-hood label and adjust oil changes to your driving conditions.