andrew lohaus

i know the premix/not to premix subject is prety much a dead horse on this board, but i wanted to look at a different aspect of it.

i have decided to go to premix because my OMP is only injecting at something like a 1:1000-1:2000 ratio
maybe thats enough, but thats why im starting this thread.

im looking for the average amount consumed since it obviosly will vary depending on rpm etc. baisicaly how much gas have you used before you need to pour in another quart of oil?

so i was wondering what some of your omps are injecting at, what would be considered a normal range, and what some of you guys may have observed interms of internal conditions Vs. injection ratio.

please tell if you have a turbo or na, s4 or s5 OMP, and what other mods you have done that might affect oil consumption.

thanks

vaughnc

Does the injection rate depend on the RPM ??

1987RX7guy

iTrader: (3)

^ Yup

andrew lohaus

yeah i know the injection depends on the rpm but im looking for the net average. in other words, how much gas have you used before you need to pour in another quart of oil.

vaughnc

The rate also depends on the viscosity. Older dirty oil is injected faster than new clean oil. I can go 1500 miles and hardly add anything. Then I may add a 1/8 - 1/4 quart every fillup until I hit 3000 miles.

On a newer broken in engine you'd probably add 1/4 - 3/4 quart per oil change. So 3000 miles @ 3/4 quart - what's that translate to?

andrew lohaus

thats it? that translates to about 1:1500-1:2000 ratio depending on gas milege. thats about what im doing and thats considered normal?

but when people run premix they are usualy using like ten times more oil around 1:100-1:200, iether they are using to much or the OMP is using too litlle. there is sucha spread in the ratios.

Steve Scheidig

I've only had my 90 Vert for a short while now, only one oil change so far, and not really sure how much oil it uses. About 2000 miles after I purchased the car I changed the oil for the first time. Never added any oil uring that time and it was about 3/4 of quart low. If I did the math correctly, which I may not have, that comes out to ratio of about 1,320:1. Right? The past couple days, I've been wondering the same thing about how much the car should use & if I should be premixing as a backup/precaution. Seems that alot of those who premix use about 100 to 200:1 ratios. If the OMP is doing it's job, shouldn't I need to add 1/4 - 1/2 a quart with each tank or two of gas? I'm thinking about premixing somewhere around 400 to one, not disconnecting the oil injection system, and calling that good.

With that said, I had a buddy in Arizone who's injection system quit/failed on him. Didn't even know it until he pulled into a rest stop on the freeway and the engine made a wierd noise when he turned it off. It instantly froze up on him & wouldn't turn over. 2000+ bucks later he had a new engine and he started premixing.

Steve Scheidig

wait my math has got to be wrong. Is this right?

2000 miles @ 14 mpg = 143 gallons
143 gallons x 4 quarts per gallon = 572 quarts
572 quarts / .75 quarts = 763

So I might be at a ratio of 763:1 if this is correct. It's been a really long day & my brain is fried.

NZConvertible

Assuming an average 18mpg fuel consumption and the recommended 1qt/1000miles oil consumption, that's an average ratio of around 200:1, which is the figure I've heard numerous times for the stock OMP.

andrew lohaus

to the top. come on people, its a little math but its good info please!

Icemark

With the S4 the injection amounts are based on throttle position rather than RPM