Quote Originally Posted by Scimmia View Post
God, I hate these discussions on regular car forums, they are always so full of speculation, rumor, and outright misinformation. I'm trying to stay out of it, but I'll just chime in about 5W-30 vs 10W-30. They are both 30 weight oils, so what does it matter?!? The 5W will be thinner at very low temps, but that's it.

If anyone's actually interested in learning about engine oils, go to the forums on Welcome
a very VERY big x2. i actually frequent that website more then this one. i was gonna bring it up but just figured it'd be wasting my time. some people here seem to "stubborn" to learn new tricks

when looking at viscositys, the first number is the cold weight, and the second number is the weight at operating temps. when you start your car, your oil is either a 5 or 10w (or very close). obviously the 5 is thinner and will flow better NO MATTER WHAT. when your engine gets up to operating temperature, they're both 30 weights. so theres no difference. you could run 5w30 in your grand prix all its life and the only thing its gonna suffer from is better lubrication at start up