Oil being dark does not mean much other than it changed color. It's not an indication of how much life is left in the oil.

 

Looking at every one else's oil change intervals I guess it wouldn't hurt to stretch it for another 2k miles

 

Oil is SUPPOSED to get dark. If it doesn't, that means that the detergents and additive-packages in the oil aren't doing their job and holding dirt, contaminants, and microscopically-small wear-particles from the engine in suspension.

 

Well I just learn something new today lol

 

I would say that is misleading advice. The factory can and does screw up things as simple as oil change intervals. I'd say the recommended service intervals should be used as a guide, but its up to you to do your own research and evaluate how you use your car. Car forums like this are great resources.

Toyotas with the engine sludge problem a few years ago, the recommended change interval for normal operation was 7500 miles. The severe duty oil change interval is every 5,000 miles. Listed under severe duty is "lots of short trips in cold weather". Well of course most people reading this say "Oh I don't operate my car like that, I don't beat on it" and assume that the 7500 mile interval is fine, despite them living up north and driving 2 miles to the store and back 5 times a week and never letting the engine get up to operating temperature. That type of behavior is murder on oil life. Now I'm not saying that this was all on the owner, but people who changed their oil more frequently never had oil sludge problems.

BMW, with their problematic N63 twin turbo V8 recently shortened the oil change interval from 15,000 miles to 10,000 miles. They were having problems with the oil being completely broken down and cooked at that mileage interval. I still think 10,000 miles is too long of an interval for that engine, as turbocharged motors tend to run hot. This one runs even hotter because the exhaust manifold and turbos are stuck in the V of the engine. BMW was also having problems with oil consumption, as in 15k miles was so long the engines would come in for service low on oil. The main reason BMW specified this longer oil change is that they started offering free maintenance for the first 2 or 3 years when you buy the car, so this was a cost cutting measure on their part that has really bit them in the butt.

So the owner's manual is a guide IMO, not the bible in terms of oil change intervals. If you are going to use the longer service intervals, be sure to use EXACTLY what type of oil you are supposed to use along with the manufacturer's oil filter, don't cheap out and buy non-synthetic off brand oil and a FRAM filter if you are going to push it to the 7500 or 10k service intervals. Also be sure to check your oil level, even a new car can use some oil in 10,000 miles

Oil technology has come a long way, and on newer cars built in the last 20 years, 3000 miles is way too soon. I change my oil every 5k miles in my car(1992 SC300), but then again I probably could push it a few thousand more miles. However I view it as cheap insurance and want to keep this car on the road for 250k+miles.

 

The factory recommendations are based upon the non synthetic oil, if I am not mistaken.

 

Actually the N63's reduction in OCI has nothing to do with the oil breaking down. It's about two things:

1. Oil consumption in engines that aren't run hard, especially during break-in
2. Checking/replacing batteries due to a flawed assumption in the design of the "efficient dynamics" charging system

The first one is pretty straightforward. Customers were getting the "check oil level" light before the service indicator light. To make the problem go away, they reduced the interval from 15k to 10k, so an oil change was due before the oil level would drop to the point of triggering the light. Ironically enough, flogging the **** out of the motor during the first few thousand miles avoids this issue altogether.

The second one is much stranger. BMW programmed the charging system to only operate during coasting, which increases fuel economy. Unfortunately, the typical American drive doesn't involve much coasting. Either we're in stop/go traffic, or we're cruising on the expressway. This was a tenuous balance on the non-turbo V8s, but worked out OK almost all the time. But when the engine was turbocharged, that meant in several situations the cooling system had to continue running after the car was switched off. This added drain upset the balance, and caused short life for batteries. The revised service schedule had batteries being tested, recharged, and replaced if necessary at no charge to the customer.

I can't tell you whether 15k is too long for turbo engines in general, as I haven't yet needed to take the valve cover off my M57. My M52TU certainly did just fine on an 18k interval with Amsoil and Mann filters (valvetrain looked brand new at 95k miles, and kept running beautifully for many miles thereafter), but obviously NA is a far less stressful environment than FI. Given the specific design of the N63, I'd tend toward caution as well.

 

Real world resutls here:

https://www.clublexus.com/forums/is-...-uoa-here.html

and here:

https://www.clublexus.com/forums/is-...oa-thread.html

There is no substitute for UOA. It tells you everything you need to know about your car, your driving, your climate, and your engine.

I run 12k mile OCIs using Mobil 1 5w-30 on my IS F and I track the car. Still shows I am just fine.

 

Ever since some of the UOA threads began popping up on the 2nd gen IS forum back in 2006/2007, i went to a 10k mile synthetic oil change interval and the car has been great. ~10 years and 110k+ later, still going strong!

 

Is there a difference between an oil change and an oil flush?

 

There is no oil flush for an engine. A flush is what they call an oil change on a transmission.

 

Credible or not, though, some shops do try and convince customers that engine-flushes are necessary to get all the sludge/sediment out of the block and oil pan. It's the same idea as flushing transmissions.

 

for my turbo 4 in the WRX I do 5000 miles or 1 year with Pennzoil Platinum and the OEM filter....doing the Blackstone UOA on next oil change.

 

didn't BMW changes the interval to 10K?

http://f30.bimmerpost.com/forums/sho...d.php?t=868291

 

I change my oil and oil filter every 5,000 miles with 0W-20 Eneos Sustina oil.