CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

2007 Mazda6 3.0 V6 oil consumption

I have a 2007 Mazda 6 with the 3.0 V6 and currently about 65000 miles that we bought brand new. I religiously change the oil in 4000 mile intervals, despite the recommened 5k interval listed in the manual (we are in Minnesota, and it mainly drives the wife to work everyday – shorter trips of city driving).

A few months ago, it started using more oil between changes. It went from using none between changes to burning about a quart every 1500 miles. There has to be something wrong. I have spoken to the dealer service dept about this (since we have a Mazda extended warranty, any warranty work will need to be done at a dealer), and they say it is within the acceptable range of oil use on this vehicle and I should bring it back every 1000 miles to record the usage levels. I asked that they change the PCV valve, and they said that it doesn’t have a standard PCV, but a larger, more expensive tube that wouldn’t have failed.

My concern, while I do regularly check my oil, is that between changes I’m using 2.5 quarts of oil. I’ve driven older vehicles with 3 times the miles as this one and have never gone through oil like this. Where is it going? Is that acceptable amount to do nothing about? Any thoughts would be appreciated… I want this car to last a long time, and since it’s still under some warranty coverage I’d like to know sooner than later if there might be a major repair in my future.

Thanks in advance for your comments/suggestions. MN_Jeff

Yes. That’s an acceptable level of oil consumption. Your owners manual might even state this. A quart of oil every 1,000 miles consumption is considered normal on some brand new vehicles.

Tester

You may want to try a different brand of motor oil at the next oil change, but do use the viscosity recommended in the owner’s manual. For reasons I don’t understand, some brands of oil in some vehicles seem to not be consumed as quickly. However, I don’t think it is a good idea to put in a higher viscosity oil because of oil consumption.
If this oil consumption increase started after an oil change, perhaps a lower viscosity oil was put in the crankcase.
If changing brands of oil doesn’t make a difference, and the car is in otherwise good shape, I would recommend living with the rate of oil consumption.

Normally, for that consumption rate I’d just say that it’s considered normal and acceptable. However, since it’s a sudden change you might want to look for a seeping leak. First I’d check the oil filter gasket mating surface. It’s possible that there’s an old gasket stuck there that’s preventing the new gasket from seating properly. It would not be the first time I’d heard of this problem.

The other thing you could do, beyond getting a set of ramps and sliding under the car with a good worklight and beyond Triedaq’s suggestion, is get some UV sensitive additive designed for finding leaks. You run it in the oil and then any leak paths will glow when subjected to a blacklight. You can buy the additive and the light at any parts store.

Post back with what you find. We do care.

I would get the PCV system inspected for clogging.
Short trips in Minnesota weather could fill it with goop.
Should be possible to clean it out without replacing parts.

Thanks guys. Appreciate the comments. I’ll check through my records and see if the change in use coincides with an oil change/possible change in brands used. I’ve had my independent mechanic do a few changes as well as the dealer.

I’m pretty sure there’s no physical leaks - I’ve had the dealer check into it, and there aren’t any drips where the car frequently parks. Maybe when it warms up some, I’ll throw it up on some ramps and look around.

Honestly, I’m mostly worried about the amount being used, as I’ve never had a car go through oil that quickly. I hope I don’t forget to check it some time and run it low. My wife has strict instructions to shut it off immediately if the idiot light comes on, but hopefully we never get to that.

Or, do I just run it out of oil once and have the warranty cover a new engine? Probably not ethical, and now the dealer has a record of me knowing it uses oil… so I’d probably lose out on that deal as well.

The warranty wouldn’t cover a new engine. Your level of use is acceptable. No problem exists. Even if it did, I wouldn’t recommend it. Changing an engine out is major surgery, and while it comes out successful 98% of the time, it still involves risk.

I commend you for your attention to your car. That level of attention should keep the car running long and reliable, even if the oil usage is on the high side of the distribution curve.

If your engine is seized or ruined because of no oil in it, their isn’t a car manufacturer in the world that will cover it unless the missing oil was from the sudden catastrophic failure of something else, like a rod rxiting through the oil pan.