Reading the original post I get the idea that your mind is already made up anyway.

You can analyze oil and the data will tell you it can go way past what conventional wisdom indicates. What the oil analysis does not show is microscopic particulate. This is what "stretches" timing chains.

As compared to the overhaul and repair costs of an MB diesel engine, oil and filters are NASTY, FILTHY cheap. In the course of the amount of time that it takes to go that extra 5K miles on the oil filter, you could cut out a few cups of coffee, or whatever beverage you like to drink and make up for it. Can you give up a few cups of coffee in six months or a year?

It always amazes me that someone will buy an EXPEN$IVE automobile that can potentially require and EXPEN$IVE overhaul and then they are obsessed with saving $20 or $30 a year on preventive maintenance.

Just call me a cantankerous old Fart, but I just don't get it.

Larry, are you able to elaborate, perhaps provide some substantiation? I tend toward longish drain intervals (10K with Delvac 1), but am not opposed to more frequent changes if I there's compelling reason.

Thanks.

No, you don't get it. All of the comments thus far have been subjective. No where did I read any comments with quantifiable information. As far as I can tell, most people change their oil and filter often because they are too worried to do otherwise. That is what I have been doing so far.

The best and most scientific advice was to do a series of UOA's and quantify how long to run the oil and filter in my engine.

I might go that route, but until then, I'll be changing my filter and oil at 4 or 5 K miles because I don't know what else to do with such little information.

I tried running up to 9-10K miles once (with my previous 617 engine) an had a UOA done (Blackstone Labs). They recommended a shorter interval due to high soot so I went back to 5K miles (using Mobile 1 5W40). I have not had a UOA done for my current engine. If you really want to know, invest $20 in an oil analysis for your specific engine.

You will probably need to do at least two, likely more analyses to determine the viability of extended-filter changes, ... or about the price of 8 oil filters.

It would seem to me that changing both regularily pays indirectly with much longer timing chain life alone. Timing chains are a good indicator or barometer as they are very sensative to any abrasive components circulating in the lubricating oil.

We never get into it much but a chain that is preliminarily wearing out also has an effect on the expensive sprockets that it drives.