While talking to fellow contributor Jimmy Nylund on the phone, the subject of oil changes came up. He had recently purchased a new pickup, and the dealer-probably to promote his service department-had offered a coupon for a free oil change. At about the 800-mile mark Jimmy took advantage of it. The service manager almost refused to do the service, telling him he didn't need to change the oil until the odometer hit the 7,500-mile mark. What's ironic about this is, some four years earlier I got the same answer when I, also having an oil change freebie coupon, requested an oil change at 632 miles on my Duramax. While Jimmy and I disagree on a lot of subjects, when it comes to vehicle maintenance, we're both in agreement that "more is better."
No matter how clean an engine-building facility is-be it the new vehicle manufacturer or a custom engine shop, there are going to be some micron-size particles left over trapped in a hidden void just waiting for oil circulation to clean it out. Special break-in lubricants used during engine assembly also are noted for plugging oil filters. Then there is the matter of initial wear during the break-in process. No matter how precision the machining operations, there is always some wear as parts get friendly with each other.
Wear isn't limited to just engine parts. Transmissions, transfer cases, and differentials also go through this break-in process in a new vehicle. However, my Chevrolet owner's manual says I don't have to change the oil for short-trip driving until 5,000 miles, or 7,500 miles for long-trip driving. My truck gets used hard at maximum GVWR most of the time. After much research through both oil companies and trucking companies, I settled on a 5,000-mile oil change period using a brand-name synthetic in my diesel. Maybe it's too long or perhaps too short, but it's something that I'm comfortable with.
I also found the section in the manual on transmissions quite interesting. If I had the Allison automatic, it would go 50,000 miles before it needed changing. Plus, there is no mention of ever changing the manual transmission, transfer case, or differential fluids. Hmm .... As with an engine, parts wear and these loose pieces, even if super-small in size, work as cutting tools. OK, superior lubricants have been developed over the years that don't break down under heat and carry more junk in the suspension, don't foam or oxidize as badly, and offer a tremendous amount of shear strength as compared to lubricants just a few years ago. But still, oil, gear lube, and transmission fluids are relatively inexpensive when compared to an engine or drivetrain component rebuild.
Now when it comes to my Jeep that sees mainly off-highway use, I am a bit more fanatical. I don't pay a lot of attention to mileage, but just use it as sort of a guideline. I change the lubricants when I feel that they need changing. Influencing factors are the air temperature, driving conditions, amount of dust, mud, or water encountered, and how hard I used the vehicle. I have changed the engine oil, the auto trans fluid, and hit all the grease fittings with less than 1,000 miles showing on the speedo from the last time this was all done.
There is a drawback, as I'm spending more initially on maintenance, and yes, I'm using more natural resources. But I figure that it evens out with those that think they can go a year or 10,000 miles between oil changes.
