transmission & differential fluid synthetic change out

[coobie]

I know this Question had been asked about 100 times before,but my truck is coming up on 15,000 miles. I would like to change the transmission and Diffs out to synthetic oils. I am currently leaning towards the amsoil products. Any info?Thanks,coobie

 

[BHolm]

Everyone has their own opinion on this so expect 100 different versions.



My '03s are work trucks. I change the engine oil every 5k miles and run Rotella. The diffs were changed to Amsoil synthetic at 10k miles and will be changed every 50k after that. I also change the t-case fluid out to Amsoil synthetic ATF on the exact same intervals. I run dino oil in the auto transmissions because they get flushed every 25k anyway. My thinking is that the fluids like engine oil and transmission fluid, that get changed on regular intervals are not in need of the extra protection the synthetics give, especially considering the cost. My only evidence that this plan works is the 240k mile '99 PSD. The auto transmission in those was supposedly fragile. Mine went 200k easy on dino oil. This is also with everyday 15k lb towing and plowing snow on a 10 acre lot in the winter. I also waited until 200k before a complete rear end rebuild. At 200k I did the rear and the transmission as preventative items, not because they had failed. That truck still works hard and has been problem free.



I do use Amsoil in a bunch of my vehicles. I have never had any problems but then who has actually had lubricant related failures they can prove? Synthetic in the transmission might be a good idea if you work it really hard. Still I run dino and haven't had a problem even with daily heavy loads and contruction site deliverys (ie muddy, rough and ugly).

 

[Tony T.]

Changing out Fluids

I changed my diffs at 15,200 miles an used the Castrol Syntec 75w-90 (full synthetic) gear oil (the factory oil that came out looked real clean also). The Castrol Syntec has the GL-5 rating according to recommendation of the owners manual. Trans I have not changed yet with 23K on the clock an probaly won't until around 30K and when I do I'll use the Mopar ATF+4. I do lite to moderate towing.



I not familiar with the Amsoil brand so I don't know if it has the GL-5 rating. I would say any of the gear oils with this GL-5 rating you would be good to go with.



I also have seen at my Dodge dealership advertizments on Amsoil ,but have never ask about it.





Tony

 

[CLAYTON]

I changed mine out with redline synthetic and it made a huge difference in the way it shifts. Big difference when towing and it shifts there is not clunk or hard shift feeling in the transmission.