Can you have good wear, and good visc at 100C if the TBN number are low or very low ? How long can you use an oil with the TBN at zero before you start to damage something ? What are you going to damage first ? And how would you know that ? Thanks
quote:Not sure I agree with that. Some engines just beat up the oil and reduce the TBN to 2 in 7500 miles or so. My V6 Camry does this and to say there is a problem I feel would not be accurate. Perhaps if there was a problem it owuld have died long before its current 161,000 miles.
Originally posted by widman: I like to see TBE abouve 4 in diesels and maybe 3 or so in gasoline engines, but that is just part of the equation. If it is dropping to those levels in less than 15,000 miles, something is wrong. Find the problem rather than figure out how low you can go
quote:I think I recall your post! Yeah, I understand exactly, I too am a Cheap Son too... This is what I would do. Pick the oil you want to use, your gonna have to do some testing... find out all the back ground info on it, and if your smart, you will start with one with a higher TBN, then just pick a number safe to you say like 75% of that number. Then run several OCI's The first pull and drain at say 3K The second run you will pull a sample too but longer than 3K, Then the third... You will find a place that your car averages... IF 75% drop in TBN is okay with you (me maybe 50% - you determine your own numbers) then this is the milage. I would also be pulling the POOR MAN"S oil test along the whole way... maybe every week or every 1-2K or whatever you feel like. Then after watching close you can sorta tell just by it when time is ready to do the drain by the way the oil is loaded-up... Again as far as my first post on the matter, if you are worried, you need something like Lube Control / Oil Extreme or whatever... I'm not endorsing any of these things, but they most likely will aid you in going longer drains.
Originally posted by Baveux: Robbie,Let me explain to you why I ask that question. I do not want to do extended interval. I just want to follow the oil life monitor on both of my cars. My latest UOA showed me that the TBN was low (1.07) however all other number, contaminents,wear were normal.-*-*-*
quote:Well the first thing I'd do is SHORTEN THE OCI and look for the problem. My cut-off is much higher, but my starting TBN is too. If I were to guess, I'd say it is possible that a BETTER and STRONGER oil (changed to) may be working overtime to clean up old gunk, and then would drop the TBN faster.
Originally posted by widman: -*-*If I had a car where the TBN was dropping so much and therest of the conditions seemed right, first thing I'd do is try a different oil.
quote:with you 1000% That's the problem with making a pree-meee decision. IMO the runs most guys go through won't consider a real run.
Originally posted by widman: That's exactly one of those conditions.... I feel you really need an oil in an engine 3 change cycles before you really know how it is working.