Quote:
Originally Posted by piper1
Can you educate me on this statement Turtle?
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If I can. There's a really in-depth report out there somewhere on a very well done study that was done by a group of automobile manufacturers (8 or 10 were involved, US and Europe and Japan) and oil manufacturers (4 or 5, IIRC). I can't find it at the moment. I should have saved it, but it's out there, somewhere, and I can't find it anywhere. It would certainly do a much better job at explaining the results than I can. It dealt primarily with synthetic oils and what happens to an engine at various mileages of oil drain intervals. Dozens, or maybe it was hundreds, of cars and light trucks were involved in the testing, and several big truck engines were in on it, too. It was very detailed, long, and the testing took place over a few years.
One of the surprising things (to the researches and to me) was that (other than at startup, of course) the vast majority of engine wear would occur during the first 3000 miles after an oil change. The engine would wear very quickly at first, then quickly taper off to almost no wear at 3000 to 5000 miles, then it would gradually rise on the wear chart along with the mileage. They measured the wear by oil analysis and by tearing engines apart and putting them back together.
As the oil got dirty, with soot dispersion and other things, wear would increase, obviously. They showed that changing the filter-only at regular intervals, and topping off with fresh oil as needed, dramatically reduced the dirty oil wear.
Again, this was mainly a study about long change intervals and synthetics, but regular dino oil was a part of it, too. It's just that as the miles went up and the wear increased, the engines with dino oil had more wear than the synthetics, which should come as no surprise, since the VI additives in dino oil wear out rather quickly. But the VI (Viscosity Improvers) don't wear out quickly enough to justify 3000 mile oil changes.
But basically, when you change the oil, many people notice a power boost with the new oil. It's about 5% across the board, actually. What happens is, the engine, after just being services, will rev more freely and is a little more high strung, Makes perfect sense, and considering it's been freshly filled with clean oil, that's what one would think would happen. But, the clean oil doesn't necessarily mean that it's better lubricated. More accurately, it's lubricated
differently than it was with the old dirty oil. The increase in power will increase engine wear right along with it. This all happens within the first 3000 miles and at that point the oil begins to get a little dirty, fills in the wear spots a little better, and engine wear decreases as things get back to normal again.
Of course, as time and miles go by and the oil continues to get dirty with dispersed soot and other contaminants, wear will continue, but it lessens over time as the engine and oil finally settle into a compromise with each other. Basically, engine wear starts immediately, with the majority of it happening at about 800 miles, then gradually decreases in the wear rate over the life of the engine.
Using different brands, types and viscosities of oil at each oil change will increase the wear because each oil will lubricate and shear slightly differently, even oils with the same specs. New oil wears differently enough as it is from the oil that was just removed. No point in introducing yet another set of variables into the mix.
The bottom line was that before there were multigrade detergent oils, changing the oil at 3000 miles really was the best thing to do. The engine wear during the first 3000 miles was nothing compared to what happened when non-multigrade and non-detergent oils were left in the engine beyond 3000 miles or so. But that was 30, 40 years ago. These days, when you change the oil every 3000 miles, you end up causing the engine to wear more than if you go longer between changes. And those who play around with different brands and viscosities of oil merely accelerate the wear.
All things being equal, a thinner oil is far better than a thick one, and a synthetic oil at room temperature will be thinner (more viscous) than a dino oil of the same weight numbers (they're not even weight numbers, so I have no idea why I keep calling them that). They all are designed to have the same viscosity at operating temperatures, anyway. The biggest difference in the weight numbers (0W-40, 15W-30) is how thick the oil is when the engine is shut off, or, when the engine is cold started.
There are as yet no standards in North America for shear stability of oils, but there are in Europe. Engine oils are designed with specific shear properties for European engines. Some people in the Americas are beginning to take note of things like shear stability and shear factors, largely because there are more and more European engines over here that have had the oils spec'd for it. Performance engines, hot engines and turbo charged engines all need a high shear oil.
When oil flows through and pass the
oil pump, cam shaft area, piston rings, and any other areas where two mating surface areas can squeeze the oil out momentarily, that's oil shear. When the oil is sheared out, the only thing left to protect things is the barrier film of oil that is put down by the VI additives. Viscosity Improvers are basically really large molecules that control viscosity. At high temperatures and high pressures, as with the mating surfaces inside an engine, these large molecules are sliced off, sheared off, thus reducing the viscosity of the oil over time.
With synthetic oil, Viscosity Improvers aren't necessary, as the synthetic oil molecules are designed from the beginning to make it unnecessary.
Viscosity Improvers do two things, one is they improve the flow of oil at starting temperatures, and the other is they will add that barrier film to mating parts to protect them. The biggest problem with this is that it doesn't necessarily do both things at the same time really well. It's ironic that when your oil gets old and begins to lose some of its viscosity it actually increases protection in some areas by being better able to lay down a barrier film. New oil can't do that very well. It's too thick, literally. Some of those large molecules get sheared off and take the barrier film right along with it.
Somewhere between 1000 and 3000 miles after an oil change, the barrier film becomes more stable and increases protection. But until that happens during those first 3000 miles, with the engine feeling kicked up a notch and putting out more power after receiving new oil, engine wear is taking place at a higher rate than happens beyond 3000 miles.
Assuming you want to go longer between oil changes for a plethora of reasons, what you're after, and what works the best in the long run as well as during those first 3000 miles after an oil change, is a good oil that is relatively thin at cold starting temperatures so it gets to the moving parts quickly, doesn't break down the VI and other additives quickly when at operating temperatures so that it will last longer, and that has a good HTHS (high-temperature high-shear) stability. Further, you can change the oil filter and top off with fresh oil on a routine basis to keep the oil cleaner between oil changes. A bypass filter does this, too.
Pick an oil and keep on using it without changing brands, types and viscosities. Pick an oil the manufacturer recommends. The mindset of "You can't change your oil too often," is not a good one to have. Change it per the manufacturer's instructions, or when oil analysis tells you it's time. Keep it clean with regular filter changes or a bypass filter.
Most of this applies to cars, light trucks and vans. Some applies to heavy trucks, but not all of it. If you use a synthetic in your big truck, then more of this applies to you. With heavy trucks, some of the traditional methods like Lucas is a good thing. But even the big engines are changing rapidly, so some of the "tried and true" might no longer work on them, either. Every last little bit of this applies to a Sprinter, though, that's for sure.
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