Many posts regarding this subject, so there's so much to absorb. In a nutshell, my 1999 Silverado (4.8L) usually doen't make much noise during start-up. Always been very smooth. But recently, we've had a brutal cold snap in sourthern Ontario. My truck, first thing in the morning sounds unbelieveably brutal. Kind of like a whining combined with some chattering. I'm afraid it's going to wake the neighbours up. Didn't sound like this last winter, or ever. After it warms up, sounds fine. I use 4.7L 5W30 with 1L of 5W30 synthetic thrown in (same brand - (Motomaster Formula 1), kind of like my own blend. Oil made by Shell. Oil change volume as per manual is 5.7L. Filter is Valvoline MaxLife which may be a Purolator Pure One in disguise (too restricitve?) Didn't use this filter last winter, no noise. Is it the filter, oil or something else. If the specs call for 5W30, can I safely use a 0W30 in the winter, or would 100% or a "true" synthetic blend help?