Gday just a side note that might help out
There is another step which is coming into the automotive world when it comes to oil changes.
There is a couple of ways now of testing or analising the oil to find out what contaminants are present. This is especially helpful before or just after you buy a new car, or when your car hits a milestone such as 200 000k's. These processes can let you know about what particles are present in the oil, where they come from and what they actually tell you about the internal condition of your motor without compression tests etc.
For example, these tests tell you what levels of bearing material are present. That way you know if you are likely to spin a bearing in the future. Or if there is excessive fuel in the oil- therefore running rich, or the oil is being degraded by constant short trips. Even if there is excessive water in the oil, which may be indicative of a head gasket about to let go.
The next thing to note is SOME oils are being produced and specifically engineered to not only reduce wear, temperatures, produce more power and clean the internals, but do it for longer. There is an oil which is guaranteed to safely last up to 40 000k's in a passenger vehicle. As long as the monitoring is done regularly so you know the oil is still safe (it is free and takes 5 minutes) this oil will not build up sludge and carbons, but infact dissolve more of these than most other oils. You think that sounds excessive- one aussie mob is producing oils which last 100 000k's safely in large transport!
Keep away from old technology oils. As a general rule, castrol and valvoline type oils have been proven time and time again to reduce power outputs, not effectively clean sludges and varnishes and generally fail when pushed to the limits- such as when a waterpump fails and you don't notice untill the guage is in the red....hence internal seizure. A good oil which is designed to accept very high temperature running will infact save your motor if you notice her running hot in a reasonable time. I have heard stories of V8 ski boats dumping their coolant and finish 20 minutes of racing, and the $100 000 motor still being in racing condition!
And fellas, please dont go too thin. Holden often reccommend down to 5w and 10w oils even for HSV vehicles. These simply do not adequately protect against wear in 800+ degree heat at the bores. If you want to qualify this statement- get your oil tested if you are running one of these. I bet you will find far more wear particles present in the oil than if you ran a thicker, quality oil. Also, taxis don't go that thin- quite often they are reaching for up to 25w60 sort of oils. And their motors are lasting over a million k's.
Hope this helps someone out
