# Service Indicator Display: fuel is only value used to determine ''load''



## QSilver7 (Aug 15, 2008)

I was researching info about the e39/e53 (X5) low instrument cluster...and ran across the info below that went into greater detail about *SIA III* (service indicator display III).

Before today, I was still _INCORRECTLY_ assuming that the same values used in *SIA I* and *SIA II* (fuel, mileage, engine temp, RPM) were still being used to determine "load".

The old SIA I formula was *e=a(1+t+r)* where:
 e = estimated mileage
 a = actual mileage
 t = 1 (if engine operating temps is below normal) otherwise t=0
 r = .5 (if engine is above 4500 RPM) otherwise r=0

So under this old calculaton, if you drove 5 miles with a cold engine @ 5000 RPM...the SIA I would calculate "e" as 12.5 miles although you only drove 5 miles:
 a = 5 (the actual miles driven)
 t = 1 (since the engine was cold and never reached normal operating temps)
 r = .5 (engine exceeded 4500 RPM)
e = 5(1+1+.5)= *12.5* estimated miles

But starting with the *1996 model year*...BMW started implementing *SIA III* where fuel is the ONLY value used to calculate "load"...see the info below for more details:


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## rrtec (Sep 5, 2008)

Good to know. Thanks for posting that!


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