Thin is in...

Automotive Tip of the Week: Here is a short version of one topic there. The numbers on the oil like 5W30 represent at "room temperature" how thick of an oil it flows like (5) and at operating temp how thick of an oil it flows like at that temp (30). So at low temps it flows like a nice thin 5 oil, and at operating temp it flows like a 30 weight oil. What is a bit counterintuitive, but has to do with how oil behaves at different temperatures, is that even though it is flowing like a heavier 30 oil, at those temps it is actually thinner than if it was a 5 oil at ambient temps. In the end none of this means much to you for your car and matters more for the engineers as long as you follow it. So why do I bring this up? Winter and synthetic oil. Synthetic oil has a bunch of neat properties but we'll talk about just one. Traditional 5W30 oil is usually made from 5 weight oil and then has additives put in it to make it "thicken" (as I just said that is actually not necessarily true) as it heats up so it behaves like a 30 weight oil at temp. Synthetic on the other hand usually goes the other way. It is made from a 30weight stock and then the additives and properties of it allow for it to flow in ways a conventional oil can not at lower temps. What this means is that the bottom number on your oil cap can be considered meaningless when you use synthetic oil. So a car that requests 10W30 (like my BMW) you can put in 0W30 and get the same/better protection as running the recommended oil. So why does this matter? Cold Start. When the engine is cold the oil doesn't flow very well and the most wear occurs. It is also when your starter has to work the hardest to fight the tension the oil creates. By using an oil like 0W30 in your car you get faster turn over, less stress on your starter and battery, and oil flow (not pressure! pressure is meaningless at low temps) is better. So your car will start and run better in cold weather, and you'll get better gas mileage if you drive short distances. Don't believe me? Or are unsure about this whole ignoring the oil cap and manual thing if you are using synthetic? Look at the bottles. Bottles like Mobil1 will say right on it "certified for use in 5W30" on a bottle that is 0W30 and they often market/label it as "green formula" or "better mileage formula" when it is just normal old 0W30. you can learn a lot more on this at www.bobistheoilguy.com if you want...