Quote:
Originally Posted by delvec03
What do you recommend and why?
|
Well, I recommend changing every 5,000 on regular gasoline, if running e-85 you want to run it down to 3,000. Since I assume you are running standard 91/93 5,000 is fine. Oil breaks down over time, Most oil gets to the end of its life around then. The longer you run your oil the thicker it gets, A 5w-30 at 1,000 miles will not be the same viscosity of a 5w-30 at 8,000. It picks up deposits, gets thicker and heavier because of it.
TBN (Total Base Number) measures how much base (as in base vs. acid) additive is in the oil to offset the effects of acids coming into the oil from combustion and other sources.
When you first start using the oil, the TBN tends to drop sharply. Then it levels out and drops more slowly after that. The lower the TBN reading, the less active additive the oil has left. When there is less additive there is less protection, combined with the now heavier dirtier oil because of the interval your oil isn't protecting much anymore.
Its best to do 5,000 interval in order to catch the oil before the TBN number drops to low.