For all those still interested in the "excessive oil change" subject I bought up a while back. After my other topic annoyingly got closed after a slightly over reacting member felt offended that I asked a perfectly reasonable question, an American friend and I, still baffled by the huge difference in mileage between oil change intervals for similar cars in the USA and Europe, we continued our research until we had an answer. My friend had an idea to email an oil company, one that wasn't biased between the two comparable places in question, so he emailed a German oil company that he uses, that sells oil in both the US and in Europe. His reasons are below.
So after all the debate and various theories, some of which I'm sure are all still plausible, the main reason is due to the high sulphur content in the US fuel. I also spoke to a friend of mine who does a lot of miles, around 75,000 to 85,000 per annum average, mostly in the UK and Europe. He told me that he changes his oil every 25,000 miles and in the 536,000 miles he's clocked so far on his 2006 Mercedes diesel, he's had no problems. In fact he said with the oil he uses, he could safely do 40,000 between changes.
Im guessing with the US switching to low sulphur fuel, you guys will start to see the longer intervals too, although it may take a while to break peoples habits. I hope this helps those who like me and my friend were still interested in continuing the debate and getting some facts and answers!
I have been researching the direct injection motors looking for a next vehicle and seem to found out that some of the motors have a problem at approx 90,000 miles with the valves needed some kind of cleaning or whatever. It does seem this could be possible because of the way the fuel is put into the system. In the older style the fuel is injected in front of the valves giving them lubrication and cleaning. Is there anybody out there that has experience of any kind with this? Would be helpful in the decision for the next car. Thanks
I know older direct injection systems had carbon build up issues. Those are a generation or so behind the ones on the market now. Timing control is better so fuel isn't getting in when not wanted, which lead to the carbon build up. Likewise, the engineers should be smart enough to use valve materials that aren't reliant on gasoline for lubrication.
Hyundai and Ford have both been using DI long enough that any major issues should have come to light. I wonder if problems with the old designs aren't getting conflated with the new ones. Like with turbos, there was reliability issues in older ones, but material science and costs improve in time. So the current turbos should be more robust and better at handling heat.