Questions and Answers
What Oil To Use??
Q. Your article on How to Change Your Oil was helpful. I am having a problem figuring out what type (weight) to use. I would like to adopt a weight that can be used in both our cars. One car recommends SAE 5W-30. Is this the same as 5W-30 ACEA G5? The other car has a chart that lists several weights from 30W to 20W-50, based on what the chart calls "ambient temperature". Living in Dallas exposes us to high temperatures, but I don't want to risk damaging the engine, as I am told could happen, if I use a higher weight oil (like 10W-40 instead of 5W-30)
Thanks
DavidA. I don't know of anything as confusing on a car as what grade of oil to use.
A good, general grade of oil to use all year and in all climates is 5W-30. By the way, the W stands for Winter, not Weight as commonly believed. Modern passenger car engines are designed to use this grade of oil.
Let's talk a little bit about what those numbers and letters mean. 5W refers to fluidity when cold (W = winter grade, remember?). The lower the number, the more fluid the oil is at low temperatures, making cold starts easier. 40 refers to fluidity when hot. The higher the number, the more viscous the oil is at high temperatures and the better it protects when hot.
API is the American Petroleum Institutes standards for motor oil. Basically SF is of lower quality than SG which is lower than SH which is lower than SJ. The S indicates it is for gasoline engines. Motor oils with the API designation C means it is for a diesel engine. Where CD is of lower quality than CF.
ACEA is the European standards. Where A is for gasoline engines and B is for diesel engines. Where A2 is of lower quality than A3 and B2 is of lower quality than B3.
All the major brands of motor oils such as Valvoline, Quaker State and Pennzoil meet or exceeds both American and european standards.
In your case, you can use a 10W-30 or 10W-40 motor oil without problems. You can go as high as the 25-W-40, but that's not really necessary unless it's an old engine.
