I have an '01 330Ci, 136k miles, that is using an excessive amount of oil. I was using BMW 5w30, but switched to Castrol 0w30 hoping it would help and I the CCV has been changed. Nothing so far has helped. I have been researching this issue through various forums I belong to and I seems the problem may be the valve guide/seals. Can anyone give me an idea what it will cost to have this work done?
First of all, why would you think that switching to a THINNER oil would help with leakage? That's nonsensical. Try a good 10W-30 or even a 20W-40 to see if that helps. Next, define "an excessive amount" for us. Many people decide that if the car leaves a drop or two on the garage floor at night that it's "excessive". For a car with your mileage, I wouldn't consider even a quart every 2000 miles to be excessive; nor, do I think, would BMW. After determining that there actually is excessive consumption, you need to figure out where it's going because there only a very few parts swaps that won't make your wallet bleed. Two of those are the oil pressure and level switches that often fail and leak on their own. These are cheap and simple to replace. Next in price are a couple of relatively easy gaskets, including valve cover and front covers. Everything else requires a major engine teardown, whether it's a crank seal or a head gasket or piston rings or, as you suspect, valve seals. There's nothing wrong with doing your own research and trying to draw conclusions, but don't overlook the cheap easy stuff first. Replace those switches if there's even the slightest doubt about their integrity. I can't tell you how many times I've seen guys planning to drop the pan and rebuild or replace a $$$ oil pump when it was actually a $ (SRSLY! They are UNDER $10.) oil pressure switch. If you spend $$$ or $$$$(!) on replacing perfectly good valve seals and THEN find out it was a leaky sensor, you'll be majorly ****ed. FWIW, older BMW valve seals did tend to leak fairly often, but we're talking 2002-era cars there. After an update in the middle '70s, the problem is pretty unusual to see in current cars - especially under 150k miles.
I can't speak of the pressure switch but as for the level sensor--on an M54 engine, simple, yes; cheap, not so much. I don't have my records handy but IIRC it was between $80-$160. Spotting a leak is trivial though, so there's no need to throw money at it if unsure. One other on that list, which often fails on the M54, is the oil filter housing gasket. OP: If the underside of the engine is wet with oil, remove the air filter housing (for access) and have a look at the left side of the engine, below the manifold and behind the alternator. If it's soaked in oil and you know the CCV and valve-cover gasket is OK, suspect the oil filter housing gasket. You have to disassemble a lot to gain access but none of it is mechanically challenging (intake, belts, fan, alternator, power steering pump [can leave connected], maybe a radiator hose, etc.). Dealers want about $500 for the job but it's a not a bad DIY unless the various bolts are a corroded mess.
I considered going to Redline 10w40. Considering how much oil I'm adding a heavier wight could not be the fix in my mind. I'm also consuming the same amount of oil using BMW 5w30 synthetic. Excessive meaning 5 quarts between 5k miles oil change intervals. BMW considers adding a quart every 750 miles normal. Which is ridiculous to me. The oil level sensor was changed with in the last 2 months. When I removed the protective tray, there were no signs of oil leaking or puddling in the tray. The head gasket is fine I believe, no chocolate milk. Valve cover gasket was replaced within the last year. Front covers? Is that the VANOS seal? If so, that's one thing I havent done. I'm leaning toward the valve seals because there have been others with 2000 and 2001 3 series that have experienced the same oil consumption. All I have replaced the cheaper parts you suggest with no improvement until replacing the seals. One person commented the difference in the size of the seals was visible noticeable, no micrometer needed. I plan on having the car diagnosed by a shop. I'm just trying to get a ball park, cost wise, on valve seal repair if that turns out to be the problem.
A 10W - or even a 20W - oil is substantially thicker than the 5W and 0W oils you've been using. Considering the cost (below), I'd certainly consider using a heavier oil at least to find out if your consumption changes. OK; I'd agree that the BMW standard might be excessive. A quart every thousand is only borderline excessive, IMO. Getting it down to a quart every 2000 miles I'd consider acceptable. Are you sitting down? Figure the cost of a head gasket job, since the head has to come off, plus maybe $200-$250 for the seals work. I'd be delighted to get through that job for much under $1000 on your car. NOW will you try the heavier oil?
$1000? I was actually figuring at least double that. If I do the work, it won't happen until the spring. I'll give the heavier weight oil a shot in the mean time. Thanks for the response.
This thread is from two years ago Sammy - if they haven't said anything since then, I wouldn't hold out very high hopes for an update - anything's possible, however.
