Very interesting info.
SUNRG, thanks for the link to the other TDI reports.
I think I saw that in another posting and was looking for it.
I'll definitely look at them carefully.
I was wondering how low is too low for the TBN and
sent the following email to Blackstone:
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Dear Blackstone,
I have 2 questions on my recent UOA reports.
1. In my recent report, C38194, you stated:
"The TBN dropped to 3.7, from 8.2 last time. This is still a strong reading."
How low is it safe to let the TBN get before any damage occurs to the engine?
2.0? 1.0?
I have not seen any discussion of this in any of your newletters or articles.
If there is any, please point me in the right direction.
2. In previous reports, C32662, C35987, and C38194, on this
Valvoline 5W40 Premium Blue Extreme Synthetic Diesel Engine oil,
why does "SUS VISCOSITY @ 210 ºF" start out at 77.0,
jump to 82.9 at 4700 miles, and drop back to 76.3 at 10,000 miles?
Are these measurements correct?
How can it jump up and drop back down?
Does this matter at all?
Thanks much,
Bill Blazek
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Their response:
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Bill,
Oil is oil and oil does most of the work of oil irregardless of the additives.
Those who sell oils, especially oils with high TBNs,
put so much emphasis on this one characteristic that it wouldn't be hard to believe that
were a TBN exhausted the oil wouldn't work any more.
Nothing could be further frm the truth.
About 35% of the oils we analyze are from piston aircraft engines using oils with
little to no discernable additive, and which have a TBN of 0.0 going into use.
These oils do fine in what is probably the most diffucult engine environment any oil serves.
Nothing bad will happen to an engine using an oil that has exhausted its active additive
to the point that the TBN reads 0.0.
In regards to your viscosity question,
I have no idea why the variance in your three samples,
but I can tell you it is of little significance. All those readings are in the SAE 40W range @ 210F, which means they qualify as a 10W/40.
In fact, most 10W/40s read in the upper part of the SAE 30W range.
You are using a quality oil and it appears to be doing a good job for you.
Jim Stark
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Any comments?
Is all the hype about TBN just that, hype?
[ March 12, 2005, 01:57 AM: Message edited by: Bill Blazek ]