So i just drove from San Diego, California to Dallas, Texas in my 1993 FD with turbos that are failing (oil in the air filter, intercooler, and intake tract). I thought i would be adding tons of oil to this car just from the turbo issue alone. My oil pan also leaks so much my subframe and all under the car is soaked in oil. I haven't had to add a drop of oil though..... Either i over filled it a quart during the oil change, my omp does not work at all, im not checking it right which i highly doubt, or a combo. Its hard to tell the oil i actually need during a change since im not stock (sakebomb 19 row dual oil coolers and a built to apex oil pan) i kinda put around what came out. Any ideas of what my issue is? The motor is also low miles. Its a reman from mazda with 10,000 maybe miles on it. No smoke out the tail pipe except during the normal cold start. I do premix. I do still have a cat. My oil leak is so bad that when i stop anywhere all the oil on the CAT and DP finally burn off and cause smoke all around the car. Its embarrassing. So i would think i would be adding 10 quarts a month and a loooong trip i just took at least a half of a quart.

 

The rotary has a lot of internal suface are and transports the entire air/fuel mix through it to the other side of the engine along with liking to run rich and being tuned rich for emissions (reduced NOx).

So lots of gasoline settles out of the intake air on the side housing and rotor housing surface along the way to the combustion chamber.

This gas is scraped along by seals and ends up mixing with the oil going past the oil seals when the side housings become distorted with normal operating temps (a problem Mazda has recently finished a study on).

The short of it is the gas ends up mixing with the oil and if you dont have OMP hooked and or oil leaks the "oil" level keeps going up as it gets more and more dillute with gasoline.

 

Another thing is the dipstick full mark is above the pan/block seam, so it's hard to get a good read on level.

On the advice of someone who pulls way more G's on track than I do, I started filling halfway up the dipstick.

This has 2 positiive effects:
1. I don't fill up my catch can
2. I can track actual oil consumption, or lack of

My engine consumes almost no oil according to the dipstick, but we all know that isn't true. As TII said, it is getting replaced by gas.

I don't need to top off between my annual 3k mile changes and I don't worry about it. Engine has been running great for 10 years.

 

Ahhhh ok, i see. I thought maybe i had some kind of terrible issue. I was a little nervous lol. I was driving across country and didnt want ti do any premature danage. A good reason to stick to a 3000 or maybe even a 2500 oil change interval has now been cemented in. Although i have been keeping up with it anyway and stopped using pricey idemitsu and started using castrol GTx. . So is it bad to use a filter 2 times since it had gas saturated oil in it? I figured on some cars they go 5000 plus so 2 3000 intervals wouldnt hurt, or am i an idiot?

 

I only do it once a year, so why risk it over a few bucks?

And I only use Mazda filters after seeing first hand that the OEM filters are made on a different assembly line than the aftermarket. OEM filters are worth the extra money. Not a place to scrimp over a few $$.

 

This is the very reason why I ran Castrol GTX and change it every 1-2000 miles, oil diluted by fuel will lose its lubricating efficiency which I assume isn't good for the bearings, in both engine and the turbos.