Steve_L

hello all!! had an import sti v5 now for 6 months and have been running it on opti+millers everytime. however, ive just had the car serviced and the plugs looked as if they had been dipped in s!!t!! i was advised to only use half a bottle or optimax alone should be ok. ive also been told that if i dont use booster, i risk crank damage. so as you can see im very confused what to do???
steve.

JohnD

iTrader: (5)

The manganese in Millers Octane Plus will discolour the plugs orange and is quite normal. I have been assured by a Millers representative that it will not cause a problem.
JohnD

Steve_L

cheers jd but how much do you use ie 1 bottle per tank??

zhastaph

Yup, a full bottle for each tank.

JohnD

iTrader: (5)

As I have an 03 STi PPP I don't really need the stuff for everyday driving but stick a bottle in before filling the tank if I'm doing a fairly quick, long run (eg up to the Autosport show and back last Sat.)
With just Optimax in I will see one or two greens on the Knocklink, which is OK. With the Millers in I generally see nothing or maybe one green if pushing in the higher gears. It is obviously smoothing the combustion to reduce the background noise to this degree.
Your V5 was designed to work on 100+ RON Optimax at 98 is a long way from this. Having said that, for normal poodling around, not using too much boost, it is probably adequate, but if you intend to give it the occasional squirt the Optimax needs a bit of help! Remember that 50 ltrs of Optimax + a bottle of Millers will still not quite make the magic 100 RON although the smoothing effect of the booster will compensate for that to a degree.
JohnD

Stiff

Often pondered on this one myself. MY96 WRX totally standard but soon to have full de-cat system. It's been in the country for 6 months now and only run on Optimax (no OB) Should I use OB when de-catted (or even before?) It runs fine, but with no knocklink yet I'm always a bit worried about taking it over 5500 revs. Heard mixed reports about OB.