Oil Change Interval

[Samiam]

Another thread, started by Gordium7, alluded to this. The 6,000 oil change interval seems high to me. If the interval was, say, 3,000 miles, perhaps complaints concerning excessive oil consumption would be fewer. I change oil/filter in my Miata at around 3,500 and at 102,000 miles it does not burn a drop of oil.

I am at 5,200 miles on my Roadster right now and the oil has dropped in the sight glass to the center and is very dark. Yet, at 4,000 mi the level was 3/4 of the way up the glass and the color was amber. It seems that a considerable degradation in the oil has occured in the last 1,000 miles. I am following the guidelines until the 6,000 service but after that I am going to follow Gordium7s lead and change oil/filter at 3,000 to 3,500. I just hope the no harm has been done by the long 6,000 interval.

Oddly, I searched the forum and found no hits for others who felt the recommended interval is too long.

I wonder what BMW's reasoning for the longer interval is?

[pjpockets]

Two to three thou is a good area to be in. Every thing I have read about oil says it starts to break down at 2000 miles. Another guide is change it when its to dirty. If all you see is dark murkey brown and no amber then dump it. Mike.

[jm1515]

Sam...BMW (and most likely Mazda, check your OM) recommend the 6k OCI because they know any good quality oil of today, used in normal and not extreme conditions, can easily protect your engine for 6k miles. Subaru does...they recommend a 6k OCI on my 98Forester.
I doubt very much the OCI has anything to do w/oil consumption....that excruciating 'Harley' thread had the reasons for consumption...if you want to wade thru the rest of the crap.
That said, your oil does start to break down the moment you turn the key, but unless you do a Used Oil Analysis, you'll never appreciate how much or how little. The dark color change is from normal oxidation (absorbtion of by products and breakdown of the base oil stock). I would not worry...it means your oil is doing it's job....
But for how long???? That is the big Q.
I use the 6k OCI on my bike, after 4 or 5k OCIs during the first 10000mi 'break-in', because after extensive reading in BMW-land, on the net, and in my OM, I feel confident that no damage will occur and the Mobil1 I use will still have way more than enough goodies left in it to protect my engine. You can search any BMW forum, as I have, and you'll never hear of any documented reports of any oil-related problems caused by using BMW's recommended OCI. A lot of people like to do the 3k thing, and that's fine.....
BTW, I use a 6k OCI in my Subaru as recommended, and at 119000mi it burns a microscopic amount of oil, always has, I think due to it being a boxer engine also...

http://www.bobistheoilguy.com/
is a great place to learn all about oil, OCIs and analysis. They have a super forum, populated by all kinds of learned people, as well as a large database of Used Oil Analysis.

[MikeCam]

While there is solid science behind oil, changes, filters, and usage it is too nearly infinitely variable among riders to matter much whether there is agreement or not.

My new rule of thumb: do what you want. You are probably correct.