Originally Posted by JohnG
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It depends on usage - on avarage how many miles do you do per cold start?
What is the ratio of idling time to driving time?
What percentage of the overall operating time is spent 'at full operating temperature'
Severe service shortens intervals. Send samples to Blackstone at 1000 mile intervals to monitor tbn and viscosity.
Doesn't matter, the GMOLM takes all of that into account.
Trouble is the GMOLM doesnt know TBN, or how much VII is in the mix, or the total volume of blowby interacting with oil, or the condition of the air filter and rate at which dirty air degrades the oil...they do lots of testing and have a waaranty that they dont eant to pay for so you can assume the algorithm to be close, but its not perfect. If you want to know rather than assume, send regular samples.