Quote Originally Posted by the evil twin View Post
Reducing tyre size will give higher RPM at 100 KPH not lower.

From heaps of surfing over the yank sites... 1700 to 1800 ish is about where they get their best fuel economy.

BenK... where did you source your 10% gearing from?

Last week I was talking to two blokes here in Perth, one with the 4L85 and one with a beefed up 4L80 and both reckon best thing ever.
If thats the go then a 6L80 should be goddam awesome as 1st is waaay lower and 6th is even higher overdriven ratio than the 4L80/5's
I just had a brand new 4L80E auto put in. As a result, Brunswick changed my diff ratios back to 4.11:1, which is why I thought that going back to 33in tires would decrease engine revs further... Is that not the case?

@AB, My mate, who services my truck is a heavy diesel fitter and when he changed the coolant in my radiator, replaced it with the stuff they use in their truck fleet. It is all coolant, not 50/50 and since using it, the needle has never gone past half way in the gauge. If you get the Castrol diesel 100% coolant, he said that that one works well.

These are the things to check:
- Check your thermostats, even tho they appear to work. One may be working but the other isn't or they may have a small blockage, like a bug or some such thing.
-Check the radiator for obstructions, holes, cleanliness. Is the front covered in bugs etc
-Check radiator fan, Viscous Hub seals for oil leaks. Fan should come on when engine is hot and should blow air fairly strongly... If fan isn't blowing strong air, chances are, its kaput.

Hope this helps mate.