Engine doesn't use oil - Oil injectors? Fuel dilution? Testing?
 

I've noticed that this engine has never been an oil consumer. I've never had to add oil in between changes. My problem is that I get a little worried about apex seal lubrication even though I always mix 100:1 TCW3 in the tank. I would like both forms of lubrication: premix and OMP.

Driving conditions: almost all commuter miles on I95, some spirited, occasional HPDE track day. I only put ~3k miles on the car a year. So, only ~1 oil change a year.

After an oil change I always try and fill just below the full mark so I can observe drop in level but that doesn't always work out. I can't remember ever having to add oil. In fact, the next time I check the oil it is usually slightly above the full mark.

When I had the engine out to rebuild it I checked the oil injectors and injector check valves. There are new Mazda plastic injector lines and zero leaks in the system. I have never had any OMP related codes.

I know that I would need to pull the undertray and see how much oil comes out of the metering pump while running to check it per the FSM.

Should I check the oil injectors without tearing the engine apart? Blow through the lines somehow?

Other thoughts? How normal is this? Could I be getting fuel dilution from side seal blow by? Should I even worry about it? :( Thanks in advance.

I wouldn't worry about it, especially with premix. You should consider yourself very lucky.

yes, considering that many people premix only and remove the OMP all together with no issues---meh.

although I would, personally, perhaps up the dosage to at least or a bit more than what those OMP eliminating owners do.


when you say "I've never had to add oil between changes" -- do you mean the oil level is not dropping at ALL?
I change my oil ~2-3k, and never *HAVE* to had between changes, but notice the level is about 3/4 when it comes time.

My Old Motor had this issue oil level would never drop . which was weird since it had a massive oil leak ( but no oil metering pump )

From what I've read it could be blowback from side seals being worn out .

or the tune being to rich , but since you have the stock ECU . I'm not sure if thats the case .

periodically check the oil and see if it smells strongly of gasoline . there is always some blow back , But check just to make sure

aslong as you premix and change the oil often you should be ok . and since you are changing the oil pretty often and not driving much .

Also if you idle in traffic alot that is supposed to cause fuel dilution , because of the rich idle rotaries have

But I just want to be like everyone else!

I've read 1 oz per gallon is about right for no OMP and I'm already a little richer than that w/ OMP. I might up the OMP settings when I get a datalogit and see how that affects it.

Right, my oil level doesn't drop at all *that I can remember*. That said, maybe I should really drive the car more regularly with a heavy foot this spring and see what happens. Problem is a heavy foot in this car = blue lights in the rear view.

I have a power FC now, but no WB or datalogit yet. That said, the engine has always done this over it's 20k mile life so far.

I put in new side seals and set clearance per the FSM, but some could certainly be near the upper end of that tolerance. Compression has always been exceptional since the rebuild. The oil does smell slightly of fuel, but that's aways been my experience with 13B's.

Thanks for all the replies.

Do you have the commander with your PFC? If so, check the OMP voltage. With the PFC, no codes will be thrown for a non-functioning OMP. I agree with you, it is important to sort this out and not just premix and forget it (although DO premix, especially until you figure out if your OMP is working).

I have and always will premix in addition to OMP.

I have a commander, based on my reading the OMP voltage should be a little over 1.0V depending on coolant temp, correct?

My old engine had such leaky fuel injectors that were diluting the oil so badly it would actually have the oil level INCREASE in between oil changes...lol!

As I recall the voltage should vary between 1 and 5 volts and should curve sort of like your TPS voltage.

Do they leak down line pressure when the engine is off? Had mine cleaned, flow tested and leak down tested while the engine was apart.

Ah, I was checking at idle or just w/ ign on. Will take a look at that screen during some driving. Thanks.

Oil dilution

I wouldn't worry about it

I also don't get very much variance in oil level over a month or two, even if I drive the car every day. Like you, I was concerned that the OMP was blocked or the system was not working, but I've verified it is actually pumping.

In the last three months leading up to christmas, using the car every other day for commuting, the oil level on the dipstick has not changed at all. When I drop the oil, I dont have a hell of a lot of dilution- no fuelly smell to the used oil and UOA supports very low dilution. I dunno. Other FDs I've owned have used noticeably more than this car. This one just does not seem to...? I've run the car for about four and a half solid years as a commuter with no signs of anything being amiss with the engine, so I'd say not to worry.

Must have been, once they were cleaned and flow tested, etc...they worked fine in the new engine.