Changing transmisson and rear end fluids
 

I have a Det. engine with 885,000 miles and was wondering what would be a good time to change fluids,I have had truck since '06 and nothing been changed just checked each pm. 2000 is trk yr.
Thanks

I run synthetic in mine and change it around 200K, Speedco usually has a deal where hey do it for around $300 I believe.

They recommend changing it at 250K if you run synthetic oil

Eaton recommends 500,000 mile lube changes when running synthetic. Some owners do it every year. So there is a quite a spread there. My comfort level is 2 years/300,000 miles. Either way you decide, the cost is not that bad. A good idea is to also have whoever does the job, to flush out the old lube from the tranmission cooler as well. Not just open up the plug and do a drain and fill on the tranny.

I don't know which type of lube is in the boxes on my truck. If it is dino lube, will it harm anything to switch to synthetic? All three have high mileage.

Going sythetic would be a good choice. Will cause no problem switching from dino version if that is what is in there. Most Eaton and Merritor trannies and rears have been factory filled with synthetic lube for the last 10 years. If we were talking about using synthetic in an engine, very high mileage might be an issue (though not usually), but trannies and rears do not have the same issues as engines, so switching would not be a problem.

Synthetic is better protection and can increase your mpg.