Quote:
Originally Posted by SnoEclipse
The SM/SL spec change is pretty stupid. In a quest to reduce the small-but-not-zero possibility that zinc/phos *might* hurt cat converters, the EPA has set up a loop that will cause a LOT of owners to change their oil more frequently.
The main reason for oil changes is to renew the additive package, not to get dirty oil out of the system. Modern oils and filters are pretty good at suspending and capturing any nasties that actually get into engine oil.
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The above info is dead-on accurate; most people just don't understand this and are convinced black oil = bad
A 5 quart jug of Mobil 1 is $26 at Walmart though (bought some this morning). As a sidenote, a few weeks ago my friend had his 8k mile old Mobil 1 from his Evo IX analyzed by Blackstone and it came back with enough additive package still remaining to be effective (3.1 TBN; anything >1.0 is satisfactory for use).