My 93 850 (non-turbo) w/ 110K burns about 1 quart of oil every 1500-2000 miles. By the time I get to the 3000 mile oil change mark, it's almost 2 quarts low unless I add some in between. The car doesn't smoke and runs well, but it's driven on the highway at high speeds mostly which probably contributes to it. I notice that it burns more oil when I use 10w30 rather than a 40 weight. My question is, should I try running 20w50 or switch to synthetic oil like Mobile 1? I'm just trying to get it to go 3000 miles without having to add any.

This car (purchased when it had 79K on it) has always burned a little oil, is that common for 850's? My BMW with 155K on it doesn't burn a drop.

My '93 850 with 190K miles does not burn oil, nor does my wifes '94 850 wagon. So I would say you have a problem (perhaps just a minor one) somewhere.

One thing to look at is you flame trap. It is commonly overlooked and if it has not been changed on a regular basis can cause oil seals to be blown due to improper pressure build up.

Which leads me to my old pickup truck ('76 GMC). I have to use straight 50 weight oil to compensate for various oil leaks as it isn't worth the expense of taking the engine apart to replease gaskets.

So first check/replace your flame trap. If that doesn't help go for the highest weight oil that your temperature range will allow.

For starters, add oil when it gets 1 quart low--don't wait longer.
I've changed dozens of cars to synthetic with 100K or more on them. The only few which leaked were already leaking (or had been very poorly maintained).
Synthetic will reduce the wear, and is much more stable (less likely to evaporate).

I have a 94 850 turbo with performance upgrades which does not burn any oil between changes. I bought the car new, and have always used Mobil 1. Your oil consumption does not sound excessive, just a bit of a drag maybe?
Do you have the previous owner's service records? They might show the reasons why.

Wills

My indi-mechanic, from his experience with Volvos, tells me that 850s tend to eat a little oil. He recommended 15w 40 after he noticed that mine ate two quarts of 5w 30 from fast mountainous driving with the A/C on, from my back-to-back L.A. to San Diego trip, start of this summer (He was flushing my transmission fluid, and by habit, checked all other fluids). I change my own oil, by the way, and just went with what the local dealership had originally used. The loss was minimal until that fateful trip that brought shocking news.

I'm not sure about 20w 50, it's not recommended in our manual, and it warns us that using different viscosity other than what is stated could shorten the life of the engine.

I also wouldn't recommend switching to synthetic at this stage in the life of your 850 engine. Between the seals and gasket where regular oil couldn't squeeze into and out of the engine, synthetic with its cleaning detergent could cause some leak.

Hope this helps. Cheers, ed850.

That amount of oil consumption is not drastically excessive as long as your plugs do not get fouled, or the car suffers other ills.

We check our fluids every week on cars with over 100k miles. Just add a bit of oil as needed.

For your own information, call your BMW dealer and claim the same consumption for your BMW, I'll bet that they tell you that it is not excessive!

The weight of oil that you use should depend upon proper lubrication of the car's engine rather than avoiding proper car care.
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2 8s & 2 7s 600,000 miles total