Hey guys, I did some laps on the road course last week so I decided to change my oil a bit early (2,000 miles). However, much to my surprise I found little pieces of what appears to be brass bearing material in the catch pan (see picture).

Here's the kicker: my motor has 15 months/20,000 miles on it (reman). Oil has been regularly changed with what Mazda recommends (Mazda 5w-20). It was broken in properly, and although I do drive it hard, I also take the proper precautions; i.e. slight warm up, cool down to even out internal temps and hot spots, rev downs when necessary, etc. It's NEVER been low or high on oil, or overheated in any way. I even pop the hood and let it completely cool every few runs. Plus rotaries like being driven hard, right?

The car still runs perfectly, and I wouldn't have known otherwise. Part of me is hoping it's residual break-in material that's been hanging around in the pan, and the hard braking/turning oriented it correctly for draining. I also flushed with a fresh quart this time which I haven't done before... Just being hopeful I suppose.

So long story... well long, should I be concerned or are particles of this size somewhat normal for a newish motor?

 

5w20 is not ok, the viscosity to low; it was prescribed by Mazda only for fuel efficiency targets etc. in the USA.
In the rest of the world at least a (5)w30 grade is advised by Mazda.
In the UK and on the European continent most Wankelexperts use/advise a (-)w40 or (-)w50 grade.
Many people use a 20w50 grade, which is better for the bearings of the excentric shaft

 

5w-20 is too thin, especially for road course use where oil temps can easily reach 240+ degrees if it is hot outside, meaning that the oil thins out even more.

No idea if that will soon lead to catastrophic failure but that much bearing material in the oil from a motor that should already be fully broken in is not good...

 

use 5w20 if u wanna ur engine die faster.

 

Arca has it right. If you're planning on doing any sort of tracking, you need to up the weight in order to compensate for the higher temps. Or if you live in warmer climate you need to increase the weight.

As for the metal, a side effect of having too thin of oil, dunno what it came from.

 

I would send a sample in to be tested to Blackstone. Has this car had an engine failure previously? It is common for people to not clean out the oil coolers after a failure so if it had bearing failure before it could be debris in the coolers from that. Also 5W20 (depending on brand) is way too weak for track abuse. I recommend a good 40. I use mobil1 0W-40 but there are a few good options. If you are cost conscious try Rotella T6 5W-40 or 10W-40.

 

I was thinking the same thing. I would drain the pan and clean it... then would run some fresh oil, and send to blackstone after 500 miles to make sure no new particles are found in the oil.

 

That doesn't look like typical bearing material. I would lean to crap from poor cleaning when they did the Rebuild.

Change the oil...and run it for a week or so...and then dump it....cut open the filter and see what you have inside

 

Thanks for all the replies. Honestly the thin oil theory makes a lot of sense . The engine was replaced not rebuilt, and I'm not sure if the lines were flushed. It could just as well have been current break-in material circling around in the ~52% of oil that doesn't get drained each time.

But as suggested, the most likely explanation is probably thin oil and high temps. Sad face. Well I suppose I'll change the oil to something heavier after a couple hundred miles and see how it looks then. Hopefully the car lasts that long.

Any suggestions as to what a good viscosity would be? I've done some searching, and even on this thread there seems to be a broad range options. I do mostly daily driving with track days every month or two, and in a fairly warm climate during the summer. If the motor lasts until winter I'll cross that bridge when I get there 😂.

 

If you want to use conventional, Rotella 15w-40 in the white jug. If you want to use synthetic, Rotella T6 5w-40 in the blue jug.

They can be had for very good prices at Walmart.

 

I use Total Synthetic 5-40

 

I use Castrol GTX 10w-30. Is there a issue with 10-30? I didn't see it being anyoes choice.

 

10-30 is old school

I always laugh at the oil threads..... keep it full of clean oil......and all will be good

 

I change my oil every 3-4k, just wish these damn oil coolers had a plug to drain..

 

You would be surprised how little oil they really have in them. In the grand scheme of things it isn't worth the work.

A large part of the oil is trapped in the rotors and lines...the coolers only hold a few cups

 

cups enough. need to do an oil change and run it for 100 miles then do another one.

 

MityVac will get most if not close to all the oil out . Confirmed when i installed my oil temp banjo bolt. Only a little dribble on the inlet side. I pull nearly 5qt out every oil change.

 

How do you use the mightyvac to get the oil out?

 

Seriously?

 

Thanks, that's exactly what I was looking for!

Apparently not!

 

5w-20 too thin? You better not tell that to my engine. 74,000 miles of whatever crap 5w-20 that's on sale on it mixed with about half a quart of MMO. Changed normally every 3k miles. Sometimes 4-5k.

I guess my engine should have died thousands of miles ago instead of running like new. Interesting.

 

Can you read? This is for a track setting. And yeah 5w-20 is too thin. There's a reason that the Japanese manual suggests 5w-30, it's because they don't have to deal with bullshit organizations like the EPA.

 

74,000 miles is nothing by today's standards.

 

And MMO is as much solvent as lubricant. Probably also affects viscosity rating to the thin side even more. My bet is his journal bearings aren't anything to brag about, even at relatively low miles. If quality oil is used, additives aren't needed.

 

Yep, it would be interesting to see the internals when torn apart.