I have a 91 camaro with a mostly stock (~260HP) 350/5.7.. has 95,000mi on it. garaged overnight, coldest startup is no colder than 40*F. valve guide seals are worn (puff of blue on startup, I know I can't "fix" this with oil) currently running M1 10w30 for about 6 months (4000mi) per change, with an AC filter. the car does have an oil cooler (the type that fits between the block and filter, and has coolant running through it). on about 1 out of every 5 starts, there is valvetrain noise (lifter) that lasts for about 30 seconds until oil hits the top end. uses a bit less than 1qt every 4000 miles Use is about 50% highway commuting (1800rpm in sixth gear (97 camaro T56 trans)), and 50% blasting around town with frequent runs past 3500rpm.. I have no problems with oil pressure - 45psi going down the highway at 1800, 30 at hot idle, 50-55 at cold startup. my goals: (1) reduce/eliminate cold startup lifter noise as much as possible (2) not signifigantly worsen the puff of smoke at startup due to the worn valve guide seal issue (3) not signifigantly increase consumption I don't care so much about motor life, as it will probably be pulled and rebuilt well before it hits 150,000. I plan to switch to a donaldson or fleetguard synethetic media filter, and want to try a different oil, to help reach my goals. thinking about m1 5w30 or maybe delvac 5w40, but i have no real brand allegience and just want to use whatever is the best attempt at my goals. my reasoning for picking a thinner 'cold' oil and a premium filter is to get oil flow to the top of the motor (and thus into the valvetrain) as fast as possible. I don't know much about the cars past, other than that it's been using M1 10w30 for the past 10,000+ miles. thoughts/advice?