The FSM says that the oil capacity of the 13B engine with the oil cooler is 5.6 litres: 4.5 litres in the sump and filter which I guess would leave just over a litre for the oil cooler, its lines and the oil galleries.

The last oil change I performed (which was the first one after I purchased the car), I drained and replaced just about 4 litres from the engine, which doesn't seem like a "full" oil change. I used a full synthetic and plan to change the oil every Fall before I store the car for the winter (I only drive the car about 1,000 miles a year); my OMP doesn't seem to work so I use a pre-mix.

Is there an easy way to drain the oil from the oil cooler or is it not worth getting that last litre out of the engine?

 

Continue to change the way you do. @4 liters is right. Oil coolers are rather delicate,less they're trifled with the better...stay ahead of the curve regarding oil changes and don't worry about the last bit in oil cooler.

 

Yes, I've read that the oil coolers are fragile. Thanks for the confirmation.

 

Any specific reason you're using synthetic oil? It's far more expensive than standard oil, and the frequency you should be changing it on a rotary (since it's being burned typically - except in your case) it pens out to be better to just change standard oil at a regular interval. The OMP thing would have me very cautious, as the OMP function is to inject more oil as engine RPM increases; that isn't covered in the same fashion as your pre-mix into the fuel.

As others have stated, the Oil Cooler on the -SE is fragile and not worth monkeying with it to try and get every last bit out. I try not to look at mine sideways, or it will start leaking from the lower bung...

 

Without getting into the discussion of whether or not not synthetic oils are good for use in rotaries, let's just say that the synthetic suits my lifestyle better. I have a small collection of classic cars (six) which keeps me busy. So anything I can do to reduce the amount of time I work on them increases the time I have available to drive them. If I can swap changing regular oil twice a year to changing synthetic oil once a year, all the better. Yes, synthetic is more expensive but the reduced change frequency makes up for it.

I know that having a non-functioning OMP is not ideal so that is one of my to-dos for this winter.

And I promise not to even look at my oil cooler.

 

John, check out Blackstone labs. For what it is worth, they recommend 1,000 miles on the oil for my 12A Rotary.

 

SteveNC,

Thanks for the link. I looked around their website and it does look interesting.

When you said "they recommend 1,000 miles on the oil," did you mean they recommend changing the oil every 1,000 miles or that you should have 1,000 miles on the oil when you test it? If the former, that's really low; even the owners' handbook says 7,500. If the latter, then that makes sense.

 

Don't worry about the cooler, if the engine is warm before you do the change it'll help the oil flow out of the drain plug better.

I also run full synthetic oil in my rotaries as well, just a personal preference. The RX-8 that I built has the Sohn 2-stroke adapter so it's injecting straight 2-stroke oil into the oil injectors which will help prolong the life of the Renesis I hope. The RX-7 has the OMP blocked off completely since it's on a carburetor currently and is getting straight premix. I would definitely put your OMP problem on the top of the list for next season. Either block it off and straight premix like many of us do, or consider the two stroke adapter kit from Sohn and use a different bottle for storing the 2-stroke oil (the sub zero start assist bottle comes to mind on a stock car).

I've never heard of changing the oil every 1,000 miles, that seems like a waste even on conventional (cheaper) oils.

 

From what i’ve read on here the sub zero tank doesn’t hold up long to 2 stroke oil, it starts to degrade

 

I suppose, using the super old brittle plastic that has had stagnant pure coolant in it for a few decades wouldn't work too well. Oh well, new tanks can be found for dirt cheap on eBay.

 

It was actually based on the wear indicators of my sample and just for my next change; hoping my next sample is better. Other vehicles I have had much longer intervals.

When I sent my last sample I had been running Rislone (Zinc additive) and blue devil leak additive. I also asked how often (months or miles) I needed to change the oil since I generally put less than 3000 miles in a year. I've heard Rotary's have a lot of gasoline blow by which can thin the oil (possibly causing the leak mine has). Also, older engines which aren't sealed as well as newer ones can have more moisture contaminates and I was worrying that I should change based on months and not miles.

The report they sent me is a PDF which I can't attach, but here is their summary:

"We suggest mileage-based oil change intervals, and 1,000 miles is our suggestion for your next run. That's because wear metals are high, especially copper and lead, which may show wear at bearings or bronze parts. Chrome is from rotor housing wear. A thin viscosity and trace of fuel are generally harmless. Zinc additive isn't necessary and won't reduce poor wear from a problem. The stop-leak product shouldn't cause harm and would be okay to use if it slows the oil leak. Monitor for issues and check back on excess wear. We'll learn more with trends."

Their reports give specific ppm numbers with a trend over time. This was the first time I have ever sent a sample for the RX-7.

 

Your report is from Blackstone labs SteveNC? I'll be tempted to send out some oil samples next season just to see how my new motor is holding up.

 

Yes, Blackstone Labs. If you have more than one vehicle I'd recommend one of the bulk plans since they can test transmissions oil too. I've had them test three vehicles and the auto trans on my RV.