synthetic oil for BMWs

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Apr 5, 2004
Atlanta, GA
My BMW has a computer that monitors the oil and driving habits to tell the owner when it is time to change the oil. Typically, the oil change itervals specified by the computer are 10,000 to 15,000 miles. I am used to an interval of 5,000 miles for synthetic oil. Is 10,000 to 15,000 miles too long? I hope to drive the car for a long time.

with a good synthetic oil the computor is an excellent and accurate guide to OCIs. Thats why BMW went to the trouble and cost of developing the system

MY02 Subaru Outback 2.5 manual (Delvac 1)
MY98 BMW Z3 2.8 manual (Delvac 1)
MY89 Porsche 928 S4 Auto (Delvac 1)

The BMW computer (at least the one in my '03 5 series) works by calculating the volume of fuel consumed. Mine counts down from 3250 litres, and flips on the "service me" light when it hits zero. If I did a lot of highway driving, I get more KM's per change than if I did a lot of city.

There are two UOA's on the board for BMW's own brand of "High Performance Synthetic Oil 5w-30". One, at low mileage in a 3-series is in tough shape at about 6,000 miles. The other is in excellent shape at around 15,000 miles. Not much data to base a trend on.

Many people on the BMW-specific bulletin boards subscribe to the view that if you drive your car either very hard or in heavy traffic a lot, then you should change your oil about half-way through the service lights, twice the factory recommendation. It can't hurt, that's for sure.

By the way, there is a calculation somewhere on this board about how to determine oil changes from your engine displacement, sump size, horsepower, etc. For my car it suggests a change at 2400 litres of fuel consumed, or about 2/3 of the BMW system's recommendation.

I posted two BMW 15,000 mile UOAs (2000 BMW 528i). They didn't look all that great (wear metals iron and aluminum were higher than they should have been), the TBN was too low, and the engine was getting dirty inside.

IMO, the BMW 5W-30 "high performance" synthetic isn't up to the task of such a long interval, and a better interval would be somewhere in the neighborhood of 5,000 to 7,500 miles depending on your driving.

But take a look at the German Castrol 0W-30 UOA on the same engine, it did much better than the BMW oil.

10,000 miles is not a problem for GC, and 15K might even be possible...
I'd suggest the Amsoil 5w-30 or 10w-30 for this application. I don't think you'll have any trouble running 10k-15k drains in a six cylinder engine with a large, seven liter sump. I run Amsoil for 15k in VW engines that have only 4-5 quart sumps ....

Dixie Synthetics
I used to have a link to how the BMW monitor works. As far as I was aware, it's just not the 'amount' of fuel consumed but takes into account variables such as frequency and number of cold starts, average engine speed etc..

Yes, you get more km's per interval if you predominantly drive highway mi's.

Is 10-15k mi. too long? It's hard to say. I used to do it with their 5-40 synthetic without problems before, but I don't think the current 5-30 can handle it IMHO and personal experience.
I don't what year model your BMW is, but I'd look for BMW LongLife-01 approval mark. The following oils will meet & exceed that requirement:

Mobil 1 0w-40
GC 0w-30

I bet there are a lot more than those two, but I can't think of other than two right now. I believe BMW LL-01 requirements are:
1. must be synthetic base oil
2. HTHS > 3.5
3. Viscosity range: 0W/5W - 30/40
4. ACEA A3/B3/B4

Good luck
Dr. T

There are probably a number of versions of the BMW monitor. I've got an '03 M5, and I actually compared the "countdown" with fuel pumped into the tank at the gas station. It was within 0.3 litres over 300 litres of fuel. No compensating for cold starts or other adjustments in my car, for sure!

The fuel comsumption calculation in the on-board-computer is made using the numbers derived from the DME engine control. They even provide an adjustment (through the "service mode" of the dashboard computer) to fine-tune it with steps of 10 millilitres per 100 KM. You can go wild getting reducing the error in the computer's L/100KM calculation to within a very precise range. You might wonder how I know... don't ask!


Originally posted by jaj:
It was within 0.3 litres over 300 litres of fuel. No compensating for cold starts or other adjustments in my car, for sure!


You might wonder how I know... don't ask!

I believe you mean 3,000 liters, which is about 793 gallons of fuel. This jibes with what I've been seeing on the E39--figure about 19-22 mpg, that's about 15,000 to 17,000 miles. This is on a MY2000 E39 528i, with the old "green bars" type of display.

The MY1999- E46 3-series have a more precise "countdown" style of oil change interval computer, starting at 15,000 miles. You can see the countdown go faster if you do a lot of short-trip driving with lots of cold starts.

As far as "how you know", I'm sure you keep very accurate records... you're not the only one... my girlfriend makes fun of me for keeping all my gas receipts on file, complete with mileage/MPG data!
My 1992 e36 was calibrated for dino oil and used a different method that was essentially a maximum mi/km corrected downward for operation below normal temperature and/or above 4000rpm.

With a generous 7ltr sump and large insert-type oil filter, I have gotten excellent UOA's at 6-8000 mile intervals with 15W-40 Delo. The current 5W-30 BMW synthetic is probably a little weak compared to the 5W-40 that it replaced.

The oil service system on the M5 really does go for 650 litres per green light, or 3250 litres when reset to full "health". Other models probably have different settings because they have different engines with different power outputs and different sized sumps. Mine went 18,500 km, or just under 12,000 miles (mostly city) on the last change. The day I rolled it off the lot with 8 km on the clock, it had 3243 litres left to count down.

On some of the E39's you can read out the "litres to go" by sitting in the drivers seat with the doors all closed, the engine off and your seat belt done up, pushing the left side dashboard button (that normally resets the trip odometer) and holding it, then slowly turning the ignition key until the instrument cluster "just" lights up (key does NOT click) and waiting about 5 seconds. The dashboard readout will tell you how many litres to the next service. Mine counts down from 3250. If you change your own oil, and the system has tripped the "service me" light, you can reset the counter from the same menu point - just hit the "odo reset" button twice more.


Long, long ago, in a universe far away, I had an E36 318is, 1992, that was a dream to drive. It ran best on 94 octane fuel (Chevron in BC, Sunoco in Ontario) and with Castrol Syntec 5w-50 in the sump. It was a great car.

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