Quote:
Originally Posted by jakeru
My fairly new (to me) 2001 base with >100k on the clock recently got its first oil change. At only 7500 miles, which was half of the manufacturer recommended change interval, I was expecting it to look more clean than it did. But more alarmingly, I was quite surprised to find the newly changed oil, after simply idling the motor for a few minutes (to charge the oil filter), then letting it simply sit for several hours (to allow the oil level to stabilize, after which I drained about a pint to optimize the oil fill level) looks significantly darker than when it went in. That tells me there is residue in the motor.
I considered using a "flush" product, but I think the risk of unknown and potentially damaging chemicals lurking where you don't want them (e.g., in the lifters) is too great. I'll instead lower my oil change interval on the next change, and monitor the appearance of how carbon-loaded the drained oil appears. I might repeat that more than once if needed, New oil (some more than others - do you research to avoid this turning into an "oil holy war" thread) has detergent properties that should help clean residue from the motor, without needing to use any "additives" or "flush" products.
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If you suspect build up, long before I would dump any aftermarket product into the engine, I would switch temporarily to a diesel oil such as the Shell Rotella T6, which is a 5W-40 0il that is both very high in detergency (required in a diesel) and in ZDDP (diesels do not have cats, so they can run high ZDDP).
When you change the oil after 3-5K miles, it will be ugly, but that is what you want.
