buoy

Its interesting you brought up that point. These external sources, mostly water vapour and tiny particles are trapped by the oil. The oil then starts to lose its lubricating properties with more buildup. The only way to combat this is to change your oil regularly and keep a nice and fresh oil filter in your car. Also the "crap" is burnt off with higher temperatures which is one of the ways the engine actually relies upon (heat) to get rid of water vapour. Synthetic oil is great...... but its not immortal. You must change your oil and oil filter often. The more often the better.

redline shockproof is pretty much the best gear oil you can get... i'm putting it in my car too. if you have trouble shifting gears and want to fix bad synchros (well, not really fix but cover up the problem) use gm synchromesh. This oil emphasises the synchros ability to function so if you are after the best possible silky smooth shift, this is the stuff that does it. however, if you really thrash the gearbox then gm synchromesh may prove to be a little bit more corrosive on your gear synchros than say redline shockproof, so its up to you.