While reading my e-mail the other day, I received the following letter from NASCAR Crew Chief Mark Salem. He has his own shop and usually has some good stories to pass on. His most recent involves a salesman for a large company. The well-educated man had his new company car towed into the shop, he said it quit on him and won’t crank over now. They found the engine seized up and not a drop of oil in it.
It had 18,572 miles on it and the engine had 2 inches of sludge in the pan with the original oil filter still on it. He said he thought all the fluids were good for 100,000 miles. His fleet manager didn’t think this was as funny as Mark did.
There is a huge risk with extended oil change intervals. Some carmakers suggest intervals of 5,000 miles, while others suggest up to 12,000-15,000 mile intervals. Today’s oils will still have much of their original configuration well past 7,500 miles. The problem with extended oil changes is not the performance of the oil, it’s that no one is checking their oil level.
If you stick to a 3,000-mile oil change interval, 75% of you will be about one quart low at oil change time. No harm, no foul. But if you decide to go to a 5,000 or 7,500-mile interval, you will still be that one-quart low at 3,000 miles. As the oil level drops, oil consumption is accelerated. So, if you ignore the lost quart, you may be another quart low in another 1,500 miles. At 6,000 miles, you could have lost over half of your oil and still have no idea because no dash lights have come on. Those of us who change your oil know most of you will go 7,500 miles and never check or add oil. And if you refuse to check and add oil, once there is no oil showing on the dipstick you will almost certainly suffer engine damage that will shorten the life of your engine.
If you have a newer model car (1996-2009) and drive short trips, use either 5W20 or 5W30 oil, depending on what your owner’s manual says. Change it every 3,000 miles. Here’s why. Every time you shut your hot engine off, the moisture in the air that is inside the engine condenses and creates about a tablespoon of water that ends up in your oil, causing sludge. The only way to remove the water is to change the oil or get the oil temperature above 212 degrees Fahrenheit when the water will turn to vapor and be removed by the PCV system.
People who drive at least 30-45 miles at highway speeds once a week, during one drive cycle, boil the water out of the oil and they can go longer between oil changes, maybe 5,000 to 9,000 mile intervals.
It’s going to take some time before I can recommend anyone extend their oil change intervals to 10,000, I’ll need to see a lot more open hoods at the gas stations.