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Oil Consumption?

47K views 30 replies 12 participants last post by  SirLuci_Alpine 
#1 ·
My 2005 manual Mazda3 is going through 2 quarts of oil a week. There's no smoke or leakage of any kind. Any suggestions on what it could be?
 
#4 ·
Most likely it is the Positive crankcase vent (PCV). Typically lasts about 100K then the engines suck oil, without burning it. The part itself is not expensive but it is not an easy job. Dealerships will do it for about $250 - 300 but call and get that in writing first.
 
#5 ·
I have been breaking my head over what is causing the disappearing oil on these cars.

I have two 2006 Mazda3 hatches. I can tell which one has been better cared for as only one of them has oil consumption issues.

Most people found the PCV valve to correct their issues, but is not the case for me... and I have not found the answer to this problem in years, just keep an eye on the oil level.

Good luck!
 
#6 ·
The engine is toast, and your O2 sensors and catalytic converters will be as well soon. Read some of the threads about oil consumption and read the threads about engine swaps. The early mazda3 engines will eventually start 'consuming' oil and there is no fix.

Sorry to be the bearer of bad news, but swapping a mazda engine with a Ford Duratec engine that is more reliable is the way to go. You'll get a lot of support on these forums as many have done the swap and already done all the hard research. I just completed my swap and it feels great!

p.s. New model Ford engines are way more plentiful and way cheaper and have much lower mileage than older Mazda engines. 2.0L/2.3L/2.5L Ford and Mazda engines share the same block, so they are very compatible with each other.
 
#7 ·
The engine is toast, and your O2 sensors and catalytic converters will be as well soon. Read some of the threads about oil consumption and read the threads about engine swaps. The early mazda3 engines will eventually start 'consuming' oil and there is no fix.
There is always a fix, im just baffled by there not being a solution even though there are so many people with this issue.
 
#10 ·
I've been on Mazda3 related forums since I bought my 2009 Mazda3 i TVE 5-Speed back in the fall of 2008; I think I've heard of a single 2.0 liter engine failing, and that was clearly due to lack of maintenance. Regarding the 2.3, as I understand it, there are two main issues; the thin/low quality cylinder liners and oil flow (both of which were addressed in the 2.5 liter engines), even still, some engines manage 200,000 miles easily, others to Tango Uniform in well under 100,000 miles, even with meticulous maintenance.
 
#14 ·
Hello, I'm new to these newer Mazda engines, but learning fast. I used to drive a 1990 MX6 w/ a 2.2L if memory is correct. Awesome car. And i put 'er through it.
Currently I've got 2 of the 2.0s in my garage (one is unknown and the other is supposed to be a 2011). It's actually my sons car. I'm not sure of the mileage, maybe 110k on one and similar on the other. Problem is both engines are salvage yard engines. He got the car with a salvage yard (junk yard in my day; but that's a rant for another day:grin2:) and put maybe 2000 miles on it and it through a rod. I'm sure neither one of these engines saw much for maintenance.
So I pulled it out and tore it down to see what happened. CARBON... really bad. throughout the engine's air path. It had the most in the intake area before the combustion chamber; thick. The one cylinder got so bad that the oil rings "apparently" got plugged up with carbon. There were too many pieces. The wrist pin didn't get anymore lubrication and the rod actually stretched on the wrist pin. The rod ended up breaking a little more than half way down.
So we rolled the dice and got another junk yard engine shipped in. Guarantee and everything :laugh:. i did a compression test and one cylinder was bad. I didn't want to deal with the company that supplied it. They said all their engines are compression checked good in order for resale. I really didn't want to go through the trouble and get another bad engine. I already planned on replacing all the gaskets anyway.
Again, i tore it down to see what i was up against. It was also full of carbon; just as bad as the other one. It wouldn't have lasted long at all.

I guess the short answer: i have no idea "yet" why these engines are carbon-ing up (I don't think that's a word). But i'm sure it has something to do with oil consumption. He was adding a quart of oil every tank of fuel or so.
I'm sure this is just a lot of wind for everyone, and i opoligize for that. I feel like i might have hi-jacked this thread. The reason I'm here is to find piston ring gap specs. I'll be sure to post back here if i figure out why these are carbon up so bad, but for now; can anyone point me in the right direction.
if you're still reading this. Thank you.
 
#16 ·
Dogbone,

Since both your cars are 2.0, were you sourcing another 2.0 engine? I'm curious as to how many miles the replacement engine you purchased had, and how much did you pay? All the local (Denver) Mazda replacement engines I could find had ~100k miles on them and were $1100. Literally only a couple of motors on the East Coast had around 40k miles on them but were $1400. They probably had been sitting for many years. I was trying to find 'exact' replacements, so that was engines in the '06-'09 vintage.

I went with a 2012 2.5L duratec engine out of a Ford Fusion. Only 20k miles for about $800, including the expensive shipping cost. Got it from LKQ online. Engine was clean as a whistle when I opened it up. But, I would expect a clean engine with that low mileage.

Daugher's 2.0L engine was in bad shape. We only owned it from 85k to 155k miles, but we took care of it during that time.
 
#24 ·
I have been using liquimoly 5W20 since I owned the car, I am nearing 250k miles now and compression is still close to original and no oil loss. I change it every 5k miles though.

I think your posts were getting blocked for the suspicious length of them, haha. I like details when its something interesting, but I have seen random advertisements that pop up on the forums.

Where I live, very few people mess around with the control units on these cars, im talking the NA cars, not the speeds. That being said, I have seen so many cars with this problem, and none of them have been messed with electronically. I personally believe it trails down to the maintenance history of the vehicle.

People who buy new econoboxes like the 3s don't necessarily buy a car to take care of it. They buy a new car for it to be trouble free. I believe the 2.3L engine is just plagued with some problem with PCV path.

The theory you have is pretty intricate, but I would have to disagree, you don't have to lose compression for oil to get consumed. I have heard the older proteges consume oil because the oil ring was stuck to the piston, but compression was still good!
Another point to that, my moms 2006 3 with the 2.3L drinks oil like like a pig, but compression is good... No smoke or leak either. might not be an issue with the rings either.

As I mentioned before, one big clue leading me to believe it is the PCV system is that my moms cars intake is covered in seemingly fresh oil, where as my cars intake is dry. I haven't checked if that oil was pooling up at the bottom of the intake, but maybe it gets burned in trace amounts under high air velocity in the intake.
 
#25 ·
This thread interests me because I serviced the valve cover gasket, O2 sensors, and spark plugs last year on my 3. I had the transmission rebuilt a couple of weeks ago and the car runs strong with 14xK miles. It had 39K miles when I bought it about 7 years ago. I have noticed zero oil consumption issues with the engine, aside from having to replace the valve cover gasket, so perhaps that's why these cars have a bad rep for doing so. I use synthetic oil changed at 7,500 mile intervals.

I was wishing I'd known about the 2.5L swap *before* I had serviced the engine; however, I'm thinking I can get another 5 years out of this car.
 
#26 ·
OK guys add me to the list of Oil hungry 2.3L owners.

I bought my car new almost exactly 16 years ago. I've done all the oil changes on the car myself. Back when I used to autocross and tow regularly I used Mobil1 (5w30 in the winter and 10w30 in the summer) and changed the oil every 3000 miles. When I stopped autocrossing and towing I bumped the OCI up to 5000 miles and when Exxon bought Mobil and switched Mobil1 to a semi-synthetic I switched to MaxLife (red bottle).

I have ~145K miles on the car now, obviously some things have broken (thermostat, a few fuel purge solenoid valves, alternator) but in general it's been very reliable.

Last time I changed the oil was about 6000 miles due to two ~1000 mile road trips but I was alarmed to only get about 1.75 quarts out. I admit I had not been regularly checking the oil because I've never once had to add oil between oil changes before.

In general though the car is still running great and just passed it's smog test a couple weeks ago.

Checked it last weekend, about 500 miles since the last oil change and it was a quart low.

So needless to say this is all very concerning to me. I'm due for new spark plugs so I will check the old plugs for signs of oil and go from there.
 
#27 ·
I own a 2006 3 S with the L3V 2.3L and I bought it as the 8th owner with 136K miles. This car was clearly abused, many junk yard parts, poorly done "mods" including a welded fart can and crap tint and no power steering fluid in the reservoir when I bought it. Clearly wasn't loved. A week or so after buying I had to replace the exhaust manifold (also did all three O2s) for a CEL, which was my first sign. I went to check the spark plugs and they were coated in oil on both sides, so replaced the valve cover gasket and replaced the plugs. Later, I have driven 4K miles since the last oil flush and it was nothing on the dipstick. I also have a well coated intake manifold and had a dirty TB before I cleaned it. I replaced my PCV valve and hose on 20 May 2023, so we'll see how it goes on the oil guzzling, but the only other way I can think of helping this thing out is either taking it apart and cleaning individual parts and reassemble, or spray a bunch of motor treatment into the intake and keep using Fuel Injector cleaner for the injectors and piston heads. I'm also running slightly thicker oil, 5W-30 SAE specifically, to see if it stops with that, which could indicate bad piston rings and/or head gasket. If you have questions, lemme know I wrote this pretty quick.
 
#28 ·
I'm all for you either starting a new thread which documents your actions -- OR -- just keep posting here. I'm interested to see how this turns out. Pics go a long way as well.
 
#31 ·
When I replaced the valve cover gasket, I cleaned the plugs and it's helped for the top (porcelin) of the plugs (mind you the gasket was replaced @137,750 in October 22), and when I checked them yesterday the top and the actual spark point is dry, but my threads were nice and lubed. I'll give 'em a clean today and get back to ya by the next time I need oil.
 
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