Premix your 8, get better gas milage

***Herblenny*** · 06-03-2009, 06:07 AM

Quote:

Originally Posted by 05rex8

you could have cleaned the fuel pump sock or replaced the pump yourself for ~$125
it does help however to have the SST for removing the pump, but not needed

I would rather spend $125 or even the $500 you spent if it meant not having to buy a new motor due to lack of lubrication

I've heard that argument when I first bought my FD back 10 years ago.. People back then told me I should be pre mixing my FD... which I never did.. and I didn't loose my engine because of the wear.. And most I know either lost their engine due to bad tune (apex seal) or coolant failure. And for NA RX7, there are people who never pre mix'd go 200K.

If you look at the design of the Renesis, it already shoots in more oil than REW.. I'm sure more oil and premix might help lube the apex and side seals, but personally, I don't think it makes much difference but who knows.. But I think it does more damage when you might either detonate because less fuel is going thru or you get break up because your pump is no longer sending enough fuel.. When I first experienced problem with my 8.. It felt like I was having ignition issues.. Which I didn't know it was the pump until I took it to the dealership.. Hence why I didn't do that job.

Chibana · 06-05-2009, 12:57 PM

There was a post over at another RX-8 forum that this issue is true when using many different kinds of oils that were not designed for pre-mixing in rotary powered cars. Idemitsu claims that fouling is common among people who use these oils, but that they have never heard of this issue happening with anyone using their pre-mix oil. Of course, they have a monetary reason to say that, but I also suspect it's true. I see an awful lot of people using ordinary two-stroke oil and such as premix, and it seems foolish to me. If you're going to do it, use one that's designed for the purpose, and has a lot of racing experience to back it up.

vex · 06-05-2009, 02:17 PM

with regard to premixing, please see the oil discussion thread in the general rotary engine forum. There's appreciable wear when using premix oil on the wear surfaces.

SLOASFK · 07-21-2009, 05:18 PM

So I get around 280 miles to the tank...is there something wrong with my 8? You guys seem to be getting more like 200 miles.

mfisher12 · 07-21-2009, 07:44 PM

I have an 86 N/A W/ the Racing beat true dual exhaust, K&N Intake, pineapple racing 5th and 6th port sleeves, light weight crank and alt pulleys, no A/C no P/S ( replaced w/ manual rack) and no air pump. I have never pre-mixed and I have 269825 original miles on the car. i get about 280 miles per tank and use 87 oct. and shift @ about 7,000 every shift (terrible but true, the injectors have been re-built more than the fuel filter has been replaced). the only thing i do is change the oil w/ castrol 10w/40 every 3 months or 3k and change the plugs every 30k or as needed.

may be just me but the best thing you can do is change your oil regularly and drive the piss out it! screw the gas mileage

mazdamaniac · 07-22-2009, 02:52 PM

Quote:

Originally Posted by Herblenny

I wanted to bring this topic back up as I believe that my cause to get a new fuel pump/filter was due to pre-mix. I've also talked to one of the GA RX8 owner who tracks and he has stopped using pre-mix on his 8.. Similar reasons to why I stopped..

So, before you start using pre-mix on your Renesis, please think twice!! It costed me close to $500 to replace the pump assembly.

Pre-mix has no appreciable effect on your fuel pump. If anything, it will increase its lifespan.
The problem is the crappy Arram pump unit Mazda used in the fuel pump assembly.

You can read about this here:

http://rotarycarclub.com/rotary_foru...ead.php?t=8540

I8U · 07-25-2009, 03:04 PM

I have to agree with Jeff, the pump itself is crap. Probably why Mazda decided to go with Denso pump in the 09's...

therighthand · 07-25-2009, 11:33 PM

Just saw this topic and thought I would chime in.

I think alot of what you guys are seeing isn't because of premix itself but rather because of the various types of Premixing you are using. You want to be making sure that injection type premix is used for injection applications and mix in fuel types are used once again in the proper application.

If you want to have no way of going wrong Motul 710 is the was to go!

06-05-2009, 12:57 PM	#47
Chibana The Michigan "WANKEL" Join Date: Apr 2009 Location: Lansing, MI, USA iTrader: (0) Posts: 61 Rep Power: 16	There was a post over at another RX-8 forum that this issue is true when using many different kinds of oils that were not designed for pre-mixing in rotary powered cars. Idemitsu claims that fouling is common among people who use these oils, but that they have never heard of this issue happening with anyone using their pre-mix oil. Of course, they have a monetary reason to say that, but I also suspect it's true. I see an awful lot of people using ordinary two-stroke oil and such as premix, and it seems foolish to me. If you're going to do it, use one that's designed for the purpose, and has a lot of racing experience to back it up. __________________ 2005 Winning Blue Mazda3s 4-door 2009 Sparkling Black Mica RX-8 GT http://www.mattharrell.net/personal/cars.html

06-05-2009, 02:17 PM	#48
vex RCC Loves Me Not You Join Date: Jul 2008 Location: Influx. iTrader: (6) Posts: 2,113 Rep Power: 19	with regard to premixing, please see the oil discussion thread in the general rotary engine forum. There's appreciable wear when using premix oil on the wear surfaces. __________________ The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group

07-25-2009, 03:04 PM	#52
I8U KONI Challenge Crew Join Date: Mar 2008 Location: Goldsboro, NC iTrader: (0) Posts: 126 Rep Power: 17	I have to agree with Jeff, the pump itself is crap. Probably why Mazda decided to go with Denso pump in the 09's... __________________ 04 TiGray RX8 MT, LS2 coil setup, 3" midpipe, HKS Hi-power 3" exhaust, TEIN S-Techs, Hotchkis Adj F/R sways, K&N Typhoon V2, Steel braided brake lines, Redline drivetrain fluids, ATE Super Blue brake fluid, Cobalt XR2/GTS brake combo, MB Motorpsorts Weapons 18x9 +45 offset, 275/35's I Support the KONI Sports Car Challenge!

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07-21-2009, 05:18 PM	#49
SLOASFK Rotary Fanatic Join Date: Feb 2008 Location: Lancaster, PA iTrader: (4) Posts: 155 Rep Power: 17	So I get around 280 miles to the tank...is there something wrong with my 8? You guys seem to be getting more like 200 miles.

07-21-2009, 07:44 PM	#50
mfisher12 Rotary Fan in Training Join Date: Oct 2008 Location: SC formally form northern VA iTrader: (0) Posts: 31 Rep Power: 0	I have an 86 N/A W/ the Racing beat true dual exhaust, K&N Intake, pineapple racing 5th and 6th port sleeves, light weight crank and alt pulleys, no A/C no P/S ( replaced w/ manual rack) and no air pump. I have never pre-mixed and I have 269825 original miles on the car. i get about 280 miles per tank and use 87 oct. and shift @ about 7,000 every shift (terrible but true, the injectors have been re-built more than the fuel filter has been replaced). the only thing i do is change the oil w/ castrol 10w/40 every 3 months or 3k and change the plugs every 30k or as needed. may be just me but the best thing you can do is change your oil regularly and drive the piss out it! screw the gas mileage

07-25-2009, 11:33 PM	#53
therighthand The Newbie Join Date: Oct 2008 iTrader: (0) Posts: 7 Rep Power: 0	Just saw this topic and thought I would chime in. I think alot of what you guys are seeing isn't because of premix itself but rather because of the various types of Premixing you are using. You want to be making sure that injection type premix is used for injection applications and mix in fuel types are used once again in the proper application. If you want to have no way of going wrong Motul 710 is the was to go!