Hey I don't see this discussed anywhere on this forum, sorry if I just suck at searching.

Chris Ott of Rotary Performance wrote a blog post in January of last year discussing the topic of premixing.

To Premix Or Not To Premix

Now, in this one, for a gasoline-driven car with a working OMP, he suggests 4 oz premix per 10 gallons gas for FC and RX-8, no premixing for FB, and 2 oz per 10 gallons for a street/weekend racer FD.

2 ounces per 10 gallons is quite a bit lower than the 1/2 ounce per gallon (5 oz per 10 gallons, then) that I've seen recommended widely in threads on this forum.

Any thoughts? Chris Ott is highly respected, so wondering if people are using his lowered recommendations now or if this went completely under the radar perhaps.

Edit: After reading that again, I realize that maybe he's saying that 2 ounces is fine if you've already upped the injection rate through the PowerFC, eh? And he's recommending 4 oz per 10 gallons otherwise? Still a bit lower than the 5 oz per 10 gallons that I see recommended on the forum, but if this reading is correct, then not nearly as deviant as 2 ounces per 10 gallons.

 

I dont see the point in premixing AND keeping the omp. The very first thing I do and recommend to those with a power fc is to delete the omp and premix .05-1oz/gallon. No real reason behind the amount, it just seems to be the concensus through all the premix threads. I've been doing this for the past 6 years and have no defects or faults to report. I've used the penzoil multipurpose whatever and I am currently using marvel mystery oil. The semi synthetic 2 stroke stuff. I only switched because where I moved to didn't have the penzoil anywhere. I've been using it for 2 years and again, no defects or anomalies to report. I mix 1:1. I would rather have more than less and realistically I don't think that's too much.

 

Premix plus OMP is overkill at best. People do it for peace of mind more than anything. I strongly feel it is not necessary in the vast majority of situations.

If your OMP fails, I can understand not wanting to get a new one for thousands of dollars. But otherwise, OMP basically over lubricates anyway. There's a huge margin in the stock OMP maps in the stock ECU calibration. I have been writing a detailed article about this that I kind of set aside for a while, but maybe I should get it out there now. The stock OMP flows way more oil than is needed for everything but sustained racing. If you floor it off a stop light for 10 seconds your apex seal hardly gets hot.

The problem is, only the stock ECU has limp mode to protect the engine when the OMP fails. So it becomes a precautionary thing to just delete it if you are not running a stock or chipped ECU. Standalone ECUs have basically no OBD, so you never know if something isn't working unless there is an open or short circuit.

Please note that this statement does not apply to 2004-2008 Rx-8. Mazda cost saved the OMP nozzle for the apex seal and paid for it in warranty claims.

 

Because when injector duty is low or goes to zero, so goes your hard seal lubrication. And I thought consensus was 1 oz. per gallon w/o a working OMP.
Eh, do what you want. I've seen engines where that stock ECU overkill apparently wasn't enough. Short of fouling or emissions concerns, I don't think there is overkill. And with WI/AI there is less concern about fouling.

 

When I opened up my original motor with ~45k miles, there was evidence of inadequate lubrication in certain areas of the rotor housings. This was with a working OMP. Ever since, I have been pre-mixing roughly .5 oz per gallon with the omp.

 

I know this is in the third gen section, but I have been think about adding a little premix to my s4 n/a for piece of mind. My question is do I need to change anything like fuel filter or pump or just dump and go?

 

No. As long as you don't "dump and go" a stupid amount. On the FD I think about .5 oz. @ gal. is the going rate with an OMP.

 

Correction to my last post. Not sure why I put .05 when I meant .5. 1/2oz to 1oz per gallon.

 

Thank you sir. It cant hurt, and as many people that give me the stink eye when I tell them I do not premix because my omp is in working order there must be some good behind it . So premix here I come, just a little anyways.