TD,

At 13 degrees stretch you would have had valves smacking pistons. I think someone made a typo somewhere. More typical is 3 degrees. Mercedes recommends replacement on OM602/603 engines when stretch exceeds 4 degrees. They also say that 1 degree is normal after ~20kmi. It's all in the manual, interesting bathroom reading...

Brian, I think the synthetic is what kept stretch so low. I question whether dino changed every 3k would provide identical results. Dino changed less often definitely makes for faster chain wear though...

Regards,

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gsxr,

The REASON that dino oil, probably not just any old dino oil, can prevent chain stretch with thorough drain and filter change at 3,000 mile intervals is that the chain wear is caused by microscopic particulate in the oil. By draining often, you keep this particulate to a minimum, thus keeping chain wear at an absolute minimum.

In fact, using synthetic and changing at longer intervals could very well allow more chain wear than dino oil changed frequently. This could possibly happen because of the microscopic particulate that accumulates in the oil over time. The ultimate would be synthetic changed frequently, but not very many folks can afford that.

I'm not sure about your comment regarding your "questioning" whether or not dino oil changed at 3,000 mile intervals would provide identical results. Are you trying to say that you don't BELIEVE that my chain went 380,000 miles with no apparent stretch?

Have a great day,

So you bought that 240D brand new, it had no stretch at 380k, and currently has 533k on it...? Wow. And oddly enough extending synthetic drain intervals seems to have no detrimental effect on chain life. Isn't that what the filter is for? The only thing that should stay in the oil is soot, where it's suspended (assuming you change before hitting the 3-4% suspension limit for most diesel oils.)

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If synthetic or mineral oil is used the oil still needs to be changed - and at the right time! Determining the "right time" can be difficult. For mineral oil 2500-3000 miles seems to offer the best protection. For synthetics, longer drains are often possible. There is NO evidence that changing synthetic oil less frequently than mineral oil is bad. The fact that my chain when 94Kmi without stretching is just more evidence this is true. For 603 engines and other engines with hydraulic lifters, there is evidence that synthetic oil will quieten noisy lifters. I determined that SOOT is the most critical contaminant in diesel oil - at least for my purposes. Accepted limit is 3% but I like to keep mine closer to 2%. That translates into 6500-9500 mile intervals for my car and that's how often I change the oil. I go this route because at this rate I change the oil every 3-7 weeks instead of every 2500 miles (1.5-4 weeks) with mineral.

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Brian Toscano

380,000 is when the engine had to come apart for other reasons. The car did not go 533,000 on the same engine without being rebuilt. The marks still aligned at 380,000 miles. This engine ran about 95% highway miles and oil and filter were changed religiously at 3,000 mile intervals. No I did not buy the car new. It had 17,000 miles when I bought it, I really don't think it had the chain replaced before I got it.

An oil filter will not trap the microscopic particles that I'm talking about. That's why they're considered microscopic. Draining the oil often is the ONLY way to keep them out.

Synthetic does indeed offer more LUBRICATION protection than dino oil. We all know that. Regardless of what oil you use, the microscopic particulate will accumulate and is not trapped by the oil filter.

Have a great day,
Change oil hot and change oil often!

Its true that the oil filter does not trap ' microscopic' particles. They float around in the oil. Most of what an oil filter catches is the goop that forms when mineral oil is run too long. However, synthetic oil doesn't create this goop in the same way. There is NO evidence that suggests that synthetic oil needs to be changed as often as mineral oil for the purposes of engine longevity.

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Brian Toscano

PEH,

Thanks for setting me straight on the chain wear issue. I was imagining the wear occured at the interface between the sprocket teeth and the chain, which is apparently not a concern. I will try harder not to step on my, err... chain, in the future. Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

The sprockets do wear out but this is visible, no measurement required. They don't often require replacement before an engine rebuild though.

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