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So let me preface this by saying that I follow all of the manufacturer's suggested maintenance and religiously get my oil changed every 5K miles. However, my 2007 Mazdaspeed6 is about due for its 120k mile service, and for the last few weeks I've noticed this weird quasi rattling sound when I would start it up first thing on the morning. It would persist under low rpms and under load for the first ~5 minutes after I'd start the car and then eventually go away. Yesterday I realized that it sounded a lot less like a rattle and more like metal-on-metal noises, as if engine components weren't being properly lubricated. I checked the dipstick and it was BONE dry; absolutely nothing came back on it.

I had a couple quarts of oil in my garage and dumped three in. This seems to have taken care of the noise I was hearing, but now I'm wondering how much damage has been done (and also how I burned through so much oil so quickly, and why the light never came on). I already had an appointment scheduled with the dealership to have this noise diagnosed, but is there anything I should have them check while it's there?

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    Definitely get your oil filter checked for metal filings upon the next oil change. – Dmitry Grigoryev Jun 8 '17 at 7:34
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    FFS don't tell the garage it was really low on oil or they might (as indicated below) seize the opportunity to blame anything & everything on that and ramp up repair costs. Paulster2's reply is accurate - if the oil light never came on, the engine had oil circulating and should be basically OK unless you were racing or something. – John U Jun 8 '17 at 12:22
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    ...by all means tell them you noticed it was losing/using some oil & that you'd had to top it up though as that's useful info. – John U Jun 8 '17 at 12:23
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It sounds as though you were low on oil, but not out of oil. Your MS6 requires around 5.5-6 quarts of oil, so if you dumped three quarts in to get it up to level, you still had nearly three quarts in it. While this isn't optimal, it's definitely not bone dry. This is part of the reason your oil light didn't come on. That and the fact most "idiot lights" don't come on until the pressure gets somewhere in the 5psi arena. Lower oil quantity will usually spell lower oil pressure, but it doesn't mean there was absolutely no oil pressure. Like I said, this isn't optimal, but would probably preclude a bunch of engine damage. Rattling parts inside the engine is never good, but some oil pressure is much better than no oil pressure. You most likely have gotten away with very little engine damage, but probably have shortened the longevity of the engine some in the process. In this case, you're probably better off not "crying over spilt milk" and continue to drive it like you always have ... well, maybe you should check the oil a little more often :o)

As for the oil usage, it could be coming from several different locations, but it seems the people on this Mazdaspeed forum say there could be oil usage at the turbo. It seems the MS6's turbo may have oil consumption at the turbo bearing. I'm not sure if it could account for the amount you're talking about, but you also hadn't stated the last time you'd checked the oil in the engine. The engine has lost however much oil it's lost since the last oil change. The problem may be the turbo bearing like the forum talks about, or it could just be an old fashioned leak. To check for leaks you'll need to get on, under, and around your engine and see what's going on. Also look to see if there is any spotting in the drive/garage floor which might indicate such an issue. If you don't see any obvious oil leaks, let the dealership tell you if they see any. This is a double edged sword, though. Some dealerships are unscrupulous in if you tell them about your overall issues in detail, they'll tell you the car will need a new engine. The only reason being to pad their own wallets due to an unsuspecting customer. Be careful what you tell them, but give them enough information they know what to be looking for ... like I said, a double edged sword. Have them at least check for oil leaks. Ask them if to check the function of the turbo, maybe. Leave it up to them to give you the skinny, but don't lead them down a path which includes engine replacement, as I don't think your Mazda is due for one yet.

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    This happened with my first car. Noticed that it was making a rattling sound a few months into owning it. Turned out there was no oil (or incredibly little, as you say). The garage filled the oil, and I got several more years out of the car. All it had to show for it was a slight rattle that persisted for the lifetime. – Obsidian Phoenix Jun 7 '17 at 14:36
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    It might help to clarify that because most dip sticks are intended to indicate whether the car has the correct level, and not to distinguish between being 1.5 quarts low and 3 quarts low, they are only made long enough to accommodate the former purpose. Being 1.5 quarts low may be harmless when driving on level surfaces, but could easily result in the dip stick being completely dry. – supercat Jun 7 '17 at 17:40
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    If they say that you need a new engine, I would recommend a second opinion – Mawg Jun 8 '17 at 8:54
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    Most cars I've owned have sounded a bit more rattly / "tappety" when the oil's been a bit low, no harm has ever come of it over 100's of thousands of miles. – John U Jun 8 '17 at 12:29
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When you visit your dealership, have them (and join in if you're allowed into the shop) examine the oil after it's drained. This is important to ask beforehand since some shops use a large funnel/collection tank apparatus that is placed under the car when it's on a hoist. If such a contraption is used, it's hard to view the oil as it flows, and it's collected into a tank and mixed with other customers' oil, making diagnosis impossible. Ask them to use a smaller catch pan or tray to allow examination of the drained oil, and also examine the filter. They hopefully can provide experienced advice, but if the oil has visible metal shavings, debris or other anomalies, that would suggest rapid wear.

I agree with others that the low-oil-pressure light cannot be relied upon to indicate low oil pressure- a failed sender, poor electrical connection, etc. may prevent the light from illuminating during a critical state; also the threshold under which the light would illuminate under the best scenario is typically far under the normal acceptable oil pressure. It's more of a critical alarm than a warning.

Ask the dealer to test the engine for oil pressure- this is typically done by first ensuring oil level is normal, then removing the oil pressure sender and installing a trusted oil pressure gauge. The engine is run at various speeds and the indicated oil pressure is compared against a table of normal oil pressure values at different engine speeds. The 'sender' is your factory-equipped sensor that is screwed into the engine block to measure oil pressure. In vehicles with an oil pressure gauge, this is the device that feeds a signal to that gauge. It's far more common for vehicles like yours to omit the gauge and rely on a single warning light. This oil-pressure test will hopefully demonstrate that your oil pump is functioning correctly- important because the oil pump is susceptible to damage from excessively dirty oil, and is critical to maintaining oil pressure.

Finally, moving forward, get into the habit of checking your oil. Immediately after getting every oil change, check the level; make sure whomever you're paying for the change is filling new oil to the proper level. Every time you stop for fuel, check your oil- for both level and color. New oil has a honey color and becomes darker over time. Maintaining your 5k oil change interval is good practice, but it's important to become familiar with both the rate at which your oil level drops, and the oil color changes, between your oil changes. This can help head off problems. Some oil consumption is to be expected, but rapid consumption may suggest poor cylinder sealing, excessive turbo seal wear, etc. Check your tailpipe when the engine starts up and rev it a bit (don't use excessive engine speeds while the engine and turbo are cold) and see if you notice white or blue smoking. Blue smoke typically indicates burning oil, and this is a sure sign of needing a mechanic's diagnosis.

The easiest way I check my oil is to grab three of the free towels your service station hopefully provides next to the windshield squeegee. Put one towel in your dominant hand and two into your other, and fold them into squares as you like, them palm them in your hands. Use them as you would a potholder, to open your hood and fix the prop rod (if your hood doesn't use springs or struts to keep it open). Fold over the two towels once, so any dirt/dust from the prop rod or hood edge that got on the square is concealed and won't contaminate the dipstick. Use the hand with the single towel to pull the dipstick out fully, and the two towels to wipe it clean. Reinsert it fully, remove it fully, and examine the oil for level and color. The two-towel hand can support the dipstick as you reinsert it to prevent a shaky hand from letting the dipstick miss the dipstick hole and strike your engine, which would get your dipstick dirty. Remember that dipstick is going back into the engine oil. Then fully reinsert the dipstick a final time, fold the two-towel square again, so no oil wipe is exposed, store your prop rod, and let the hood drop. If you fold the two towels enough times, you will have enough thickness to keep the oil off your hand and have one fold remaining to keep the oil off your prop rod as you store it, and both your hands will be clean afterwards. You'll find your own way of doing it- the key is to get into the habit of checking it regularly. Good luck at the dealer!

  • Great first suggestion and overall answer! +1 – dalearn Jun 7 '17 at 15:14
  • " Maintaining your 5k oil change interval is good practice" - that depends entirely on the car, and possibly on the climate conditions where you are. In Europe, many modern cars, oil changes specified at 18k miles or 30k km in the handbook. On my current car the oil looks perfectly clean after 18k miles, and has never needed a top up between changes. I check the level about every 4k or 5k miles "just in case", .but certainly not at every fuel stop! But it doesn't get run on "farmer's oil" - only the recommended grade, usually 0W-30 or 5W-40 for those types of engine. – alephzero Jun 7 '17 at 22:55
  • That is the most elaborate, detailed and informative description of a 30 second process I have ever read. Kudos. – 3Dave Jun 9 '17 at 0:13
  • @alephzero Given that OP was unaware his oil level was potentially dangerously low, for possibly an excessively long time, I think my advice to him to check his oil level at every fuel stop is warranted. Assuming his last oil change was filled properly, oil is disappearing from his pan somehow- by leakage, consumption, etc. Gathering data points on his oil levels over time will help identify the rate of that loss and avoid the problem he described. Waiting 4k-5k miles in between level checks will not help him; it will contribute to, not address, this problem. – Mike Mokry Jun 9 '17 at 14:35
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Running an internal combustion engine out of oil is just about the worst thing that can be done to it. If the crank case and filter hold 4 quarts, and you had to add three to bring it up to level on the stick, you may very well have done serious damage to a number of things, but mainly the crank shaft bearings, and cam shaft lobes and bearings. Without opening up the engine and actually looking at the components, it is very hard to tell how much and had bad the damage is. What normally happens is "scoring" of the crank shaft journals, and cam shaft lobes and bearings. This is actually a burning of the surface causing it to become brittle and much more prone to early failure. When the oil is drained be sure to have the oil checked for bits of metal, this can be done by draining the oil into a completely clean container, then slowly pouring the old oil from the original container into a kitchen strainer lined with a few paper towels. As the oil filters through the paper towels any bigger metallic pieces will lodge in the paper towel. If this is the case, you may have really damaged the crank or cam. As for the idiot light not coming on, a number of things could be to blame. The sensor may be bad, have a loose wire, or even be cracked and leaking oil out. You need to take it to a professional not Jiffy Lube or someplace like that, A dealership may not be as good as one would hope. Always check for Better Business Bureau ratings for a shop. A few bad ratings is a indicator that this may not be your ideal location. Depending on the make, model, and year taking a look inside for a ASE rated Mechanic shouldn't take more than 4 hours shop time.

A good addition to the engine would be a magnetic drain plug, they tend to catch metallic bits that may have failed. Again anything large here is a indicator that you have serious damage.

Good luck and I hope I have answered your question to the best mechanical satisfaction.

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You could have them check, with a gauge, the oil pressure (suggest using a gauge otherwise they look at the light and say its fine).

But, any resulting damage will only be found on stripping the engine, what is certain is that you will have reduced the expected life, however, by how much is difficult or impossible to predict. It could fail in 3 days, months or years.

  • You don't have to completely strip the engine apart for this. On that car, the oil pan can be removed with the engine in the car. Yank the rod caps, plastigauge away. (Of course, at that point major damage should be evident just via visual inspection.) It's not a FUN process, but a lot cheaper than pulling / dropping the motor. – 3Dave Jun 9 '17 at 0:16
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I am the owner of an 06 Mazdaspeed 6 that I have had for almost ten years. As others have already said you probably didn't do any damage if you never saw the oil light come on. This sounds to me like an issue with your timing chain and or tensioner. This is a common issue on these cars and it's possible yours was never updated/replaced. The noise starts as a rattle and eventually gets worse as the chain is loose enough to slap around and hit the valve cover. You can actually check the chain tension by taking off the oil cap and reaching your finger in? Does it have slack? If it does, put the cap back on then drive the car for a mile or two then check again to see if the chain is tight. I'm guessing it will still be loose. You should also take a look at mazdaspeedforums. There is a ton of knowledge on that site. Best of luck.

  • The timing chain tensioner would explain a rattle, but not the oil loss. – 3Dave Jun 9 '17 at 0:14

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