Browse all motor oil guides, reviews, and troubleshooting articles
Synthetic vs. conventional oil: which do you actually need? Here's the cost-per-mile math, a 5-question decision tree, and the honest answer for your engine.
RAM EcoDiesel owners ask this every week. The answer is more nuanced than the forums suggest — MS-12991 actually traces back to a different ACEA family.
Valvoline Advanced runs about three bucks less than Mobil 1 per 5-quart jug. Both are API SP. Where the difference actually shows up — and where it doesn't.
Both meet ACEA C3 and stack OEM approvals across BMW, Mercedes, and VW. Where they actually diverge — and which one belongs in your European garage.
Both promise 15,000-mile drain intervals. The chemistry, the warranty, and the BITOG used-oil data — what actually holds up across the long haul.
Severe service kills the marketing claims. Here's how Mobil 1 Extended Performance and Castrol Edge actually compare under towing, heat, and short-trip duty.
Full synthetic vs. synthetic blend: when the upgrade earns its price and when it doesn't. Includes cost-per-mile math and engine-type guidance.
Both meet the Honda 0W-20 spec. The real question is how each handles the 1.5T fuel dilution issue and the hybrid's heat profile. Here's the data.
Six BMW Longlife-04 approved 5W-30 synthetics that actually carry the LL-04 stamp — ranked by availability, price, and OEM approval depth.
ACEA C3, C4, and C5 all look like the same family — they're not. SAPS limits, HTHS viscosity, and which European cars actually need each one.
How long does synthetic oil last? 7,500–10,000 miles in normal driving, up to 15,000 for extended-drain formulas — but time runs independently of mileage.
High mileage motor oil adds seal conditioners, antioxidants, and extra viscosity modifiers. Here's when it helps, what to expect, and which to buy.