I am about to change the tranny fluid for the first time (since I've owned the truck) and am curious to know what the readers of this board think of using synthetic's. I presently use a synthetic motor oil.

 

Rick,

I have used Mobil-1 ATF before in a Chevy Blazer and had good results with it. The shifts became more positive, quicker and smoother. I did the swap over at 19k, so the original fluid was still in good shape. Not like comapring a swap with a tranny with 50k miles on the fluid.

I am currently using Mobil-1 on both my vehicles trannys', both manuals, though.

If you regularly do a bunch of heavy hauling, or towing, I think it is a really good idea, from the viscosity breakdown aspect. ATF is not like regular motor oil, it does not get thicker with temperature increases, it gets thinner. This means that the shear rate is higher, and does not coat the internals as well (i.e. metal shavings develop.)

Good Luck,
David

 

Correction, no lubricant gets thicker when the temperature goes up, until it starts to oxidize or boil away. Then it will be forming sludge.

Reference. All oils get thinner when they are hot. Difference in multi-vise oils is they only get as thin as the second number.

IE a 5w30 will only get as thin as an SAE 30 wt at 100 degree C.

Synthetics in your transmission will work great. I have a friend that has put Amsoil in his F250. His trans temp never gets over 180 F. Even pulling a gian 5th wheel RV trailer up mountains.
Before he switched he would often see temps in excess of 220-250.

Temperature is what kill ATF. That is because it oxidizes and loses it friction characteristics.

 

HI!... I've been running REDLINE synthetic tranny fluid in my truck for about 2 years with no problems. I also use REDLINE synthetic oil in my rearend.

 

I put in Amsoil transmission fluid and could immediately feel a difference in the stick when shifting my 5-speed. I'm convinced it is better fluid than what was in the truck before.

Good luck. I'm staying with synthetic for life.

Hunt4Fun