agreed. odd how the recommended intervals doubled once BMW started paying for the oil changes.

i do my own changes between the freebies. i also will take my BMWs to an independant if i can't get to the change myself.

so just for my own education, what oil is in a BMW diesel? and how many quarts? my Ford takes 15qts. / every 5k -6k miles religiously.

For 20 bucks you can purchase an oil sampling pump. For another 20 bucks you can get your oil analyzed by an independent laboratory. The pump utililizes a 1/4" plastic tube you insert down the dipstick tube and draw a sample directly into the sample bottle for analysis.

Fill out a data sheet, put it in the mail and monitor the condition of the oil as well as the engine.

Analysis report includes 10 wear metals; 3 contaminant metals; 6 multi source metals; 5 additive metals, and viscosity, water, fuel dilution, soot % and TBN (Total Base Number).

Alternatively, you can provide a sample bottle to your servicing technician and ask that he obtain a sample after approximately 1 quart has drained from the crankcase.

If you are going to keep a vehicle I strongly suggest monitoring. You can learn such things as fuel dilution, high or low viscosity, excessive wear metals, air filter issues (excessive dirt), coolant contamination etc. and have a tool that allows one to gain confidence in extending a drain interval out if you are so inclined.

Oil analysis is routinely utilized as a valuable tool to assess performance and condition of lubricants and machinery in any application where the asset represents a substantial investment, or there is potential loss of production/downtime. A BMW diesel certainly qualifies as a candidate for periodic monitoring.

nah I don't agree that I'm taking a big chance at all. I've got another diesel with 450,000k's on it that I've serviced myself for years around every 5,000k's depending on the usage so I have a decent idea of maintaining them. they're very different engines and the state of the oil after specific intervals is also very different. I agree that a visual test isn't enough to draw a 100% conclusion though but I'm happy with the information and knowledge that I have to continue as I am.

and we don't get free oil changes/servicing in australia, there's actually more incentive here for them to encourage us to come in for servicing more often than they do.

This seems to be an eternal debate with no one ever coming to a firm conclusion. The only thing I will say is that there are plenty of cases where people have had problems using the manufacturer recommended intervals (Chevy in the 1980s where they lengthened and then had to shorten the interval, BMW in the 1990's when the filters broke down and clogged engines, many different engines in the early 2000's with oil sludge problems, etc.), but I have never heard or or seen a single case where anyone had a problem because they changed the oil sooner than the manufacturer's recommendation.

It's a personal choice and probabilistic... I am sure some people could not change their oil for 50,000 miles and honestly claim they had no problems.

But if you happen to know a professional mechanic, ask him what car he would like to own if he could have any car he wanted. Then ask him how often he would change the oil in that car if he owned it.

I like it! Who do you send it too? I have a fluids pump but I used it to pump tranny fluid in the past. Guessing I need another one?

Destination: Moon,
I've sent you a private message regarding your inquiry.

ok, now i am confused. if i remember my HS math 5k kilometers would be about 3100 miles. or is it the other way? 8k miles?

either way that is a reasonable interval. 31 thousand kilometers seems a bit excessive to me however.

I don't see much similarity between '80's Chevrolets and late model BMWs as far as engine technology goes.

Filters failing is related to filter manufacturing, not duration (although I am sure a longer duration fails more of them if they aren't made correctly).

Speaking as an engine guy, with a mechanic and mechanical engineering background, from a family of professional mechanics, who owns the two cars he wants to, I just changed the oil in both our BMWs. I cut it off at 2 years, and changed them both early, before the lights were out. 23,000 km for the 535, and 22,000 km for the X3 3.0. Both running great, and I plan to keep them.

23,000 km = 14,291 miles; 22,000 km = 13,670 miles, both are well within BMW's OEM recommendation of 15,000 mile change intervals

alright fine. i now understand the math. thanks. .62 miles is roughly a kilometer.

but let's get back to the original question. in the case of a diesel motor, specifically a BMW diesel motor, should one change the oil earlier than the prescribed 10k mile range?

am i incorrect in my opinion that a diesel motor relies on oil performance more than a gas version does?