Dear Car Talk:
A friend of mine has claimed that there’s no reason to change oil. He basically changes the oil filter, and adds a bit of oil if needed. He claims that the oil doesn’t break down, and just needs to have a new oil filter periodically. Your thoughts? – Mel
RAY: Well, the Mechanic’s Children’s College Fund wholeheartedly endorses your friend’s advice, Mel. Because an engine rebuild a month can put a kid through Harvard.
Oil does break down over time. Is motor oil better now than it’s ever been? Yes. Is synthetic oil even better? It is. You might be able to go 10,000-15,000 miles (that’s a year, for most people) between changes now with synthetic oil, whereas 30 years ago, we recommended changing your oil every 3,000 miles.
But eventually, the molecular structure of the oil does change. Oil is made up of long-chain hydrocarbons that, miraculously, cushion the metal parts of your engine that rub against each other thousands of times a minute. And when those chains break apart, the oil doesn’t do nearly as good a job of providing that cushion.
Plus, heat and oxygen combine with the oil to increase acidity and, if left long enough, it forms varnishes and sludge in the engine. And adding an occasional quart of new oil doesn’t do anything to improve the old, broken-down, acidic oil that’s still swimming around in there. Your buddy may have a quart of oil in his car that’s been circulating since the Nixon administration.
And while the filter will trap any large particles (or rocks or small children) that the oil picks up in its circulation, the filter won’t do anything to prevent the oil’s molecular breakdown.
So if you have a car that you want to keep for a long time, you absolutely should change the oil at the recommended interval.
The other reason your friend’s approach is silly, in my opinion, is that it’s a messy pain in the neck to remove and change the oil filter. Once you’re set up to do that with your ramps, your drain bucket and your wrench, and you’ve already got oil running down your sleeve, why not take the extra three minutes and drain the oil, too? It’s like taking the time to sit on the toilet but refusing to pee. It doesn’t make sense, Mel.
Ray offers a third option for stopping on a hill
Dear Car Talk:
I drive a 2005 Subaru Outback and live in a very lovely and hilly town. My Outback has an automatic transmission. When I’m stopped at a red light facing uphill, I sometimes hold the car by lightly touching the accelerator. Sometimes I use the brake pedal. When I do use the brake pedal, the car will roll back slightly before the transmission can grab on and move the car forward. Which method of holding the car on a hill is less detrimental to the transmission? To hold or brake … that is the question. Thanks. – Fritz
RAY: That’s the question, Fritz. And the answer is: It hardly matters.
Automatic transmissions are designed to “slip” when you come to a stop. If they didn’t slip, the engine would stall, just like it would if you were driving a car with a manual transmission and came to a stop while still in gear.
So, slippage – with automatic transmission fluid absorbing the power of the engine and turning it into heat – is just part of life when you’re an automatic transmission. And from the transmission’s point of view, there’s not a great deal of difference between slipping a little bit while holding the car on a hill and slipping a little bit more, for a shorter time, when you roll backward and need to change direction.
If those were my only two choices, I’d probably choose to let it roll back. But fortunately, those are not your only choices, because they both have downsides. If you use the gas pedal to hold the car on a hill, you probably have to rev the engine up to 1500 rpm or more to stay in place. If you do that frequently, you’re wasting a lot of gas. And if you use the “roll back and then go forward” approach, if the hill is steep enough, you could roll back right into the grille of your local mob boss’s brand-new Lincoln Continental.
So your best bet, since this is an everyday occurrence for you, is Option 3: Learn to use your handbrake while waiting for the light to change. When you arrive at a light, pull up the handbrake, and let the handbrake hold the car in place. If there’s traffic behind you and you want to be “ready to go,” you can even hang on to it, with the release button engaged while you wait. And when the light turns green, just release the handbrake as you step on the gas, and you won’t roll backward.
For those who don’t have a pull-up hand brake like Fritz’s Outback does, you can accomplish the same thing by “two-footing it”: Use your left foot to hold the brake pedal while you wait, and then ease off it as you step on the gas.
Problem solved! And now that we’ve eliminated this existential source of worry for you, Fritz, we hope you’ll have more time to contemplate some truly important things – like global warming, net neutrality and who Jon Snow’s mother is on “Game of Thrones.”
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