One mechanics opinion about oil

twodownzero wrote:

philh wrote:
Actually doing oil analysis, as shown above, shows that oil is good for much much much longer than "opinions".

Just got mine back. I was a little worried as I left the oil in the engine for 14,227 miles (and over 3 years!). Oil analysis looked about like you see above, my oil was sooty but still had a TBN of over 7 and could have gone another few thousand miles. The oil was Rotella T6 5W-40. Filter was a Fleetguard Stratopore.

I won't let it go that long next time (prefer to change it around 10k), but the data speak for themselves. It was not only fine, the oil was protecting the engine just as well as when I poured it in.

I did mutiple oil analysis on my 04.5 duramax and now on my 15.5 duramax. analysis when the oil life monitor said near 0%. Usually around 7K miles. In EVERY case using conventional oil analysis showed TBN still high and other indications recomending I could easily go 10-15K miles between changes.

I've done the same thing on my 2 1997 cars, 7500 miles conventional oils, TBN high, no contamination, again, easily go to 10K or more.

New oils and new engines are far better than the days of 3K or even 5K oil changes. At least on GM and my european cars, the oil life monitor is EXTREMELY conservative on oil change intervals. Follow it and do an oil analysis and I suspect you will find the same.

One car is now at 190K miles and uses maybe 4 oz in 7500 miles, 04.5 Duramax is at 180K and also uses maybe 4-6 oz of oil in 7500 miles or so. 15.5 is only at 45K similar.