[MENTION=66316]1engineer[/MENTION], I undstand that changing diff oil before the maintenance schedule may not be of much benefit, but is there any detriment?
Yes, there are some detriments:
1. It is based on your perception, not engineering science. Science trumps perception every time.
2. It uses a finite resource, petroleum, unnecessarily. Both at the front end to obtain and refine it, and at the back end to dispose/recycle/reuse. Each step takes energy, and unnecessary energy use is... unnecessary and has a cost to society and the environment.
3. Each time you do unnecessary maintenance you introduce more possible human error in doing that maintenance (improper fill, improper torque, improper procedure, etc.).
4. It can give you a false sense of security, thinking you are the uber maintainer, whereas you really are the person who does things with no rationale, no science, no rhyme or reason. In short, you think you're god, but you're actually the naked emperor.
Its a free country, but just remember what Forrest Gump said: stupid is as stupid does...
BUT, there is one reason to ignore the Toyota maintenance schedule - it might make you feel good and/or better about yourself.
:focus: