Replacing Tranny in '90 Sub, Do I run Synthetic? looking for Tips and Tricks too

kd0ezq

New member
After a very long and expensive week, I will be replacing the 700R4 tranny in my '90 V1500 Suburban. I am getting an upgraded 700R4 with a shift kit, upgraded clutches and bands, sun shaft and bearings. I am contemplating running synthetic fluid in it.

I have reasonable access to either Mobile 1 fully Synthetic or Royal Purple Max ATF. Does anyone have any expirience with either of these? Will I see a difference between the Synthetic stuff and regular ATF?

Royal Purple is about $15 a quart, Mobile 1 is $10 a quart.

Does anyone have any tips or hints to tranny longevity? This is my DD, I am running 265/75 16's and have 3.73's. Future plans include 33's.

Thanks for the help!
 

Rot Box

Explorer
Can't comment on synthetic ATF, but do yourself a favor and install a big ol' trans cooler (even if you have the one in your radiator) and also install a temp gauge. Get familiar with how a the torque converter lockup functions. An unlocked torque converter at cruising speeds (common with tall gears and larger than stock tires) puts a lot of strain on the torque converter and that translates into excess heat--the number 1 killer of a 700R4.

I prefer the plate style vs. the fin/tube style personally. http://www.summitracing.com/search/...on-oil/Cooler-Construction/Plate/?Ns=Rank|Asc
 

xpndbl3

Adventurer
just run old dex 3 and change it often, pocket the extra and smile. Get a deep trans pan with fins, preferably aluminum, run a BIG aftermarket trans cooler as well and install a trans temp gauge. The money you'd waste on the fluid can be put towards these upgrades.
 

poriggity

Explorer
Personally, if I was going to go with synthetic, I'd do Amsoil. If it's a newly built trans, I'd definitely go synthetic.
 

kd0ezq

New member
Got the Transmission installed last weekends without a hitch. Ran Dex 3 and added a bottle of Lucas ATF additive as per the guy that rebuilt the transmission. I also put a B&M External Cooler on it. I am going to run it for 5k then drop the fluid and put on the B&M deep aluminum pan.

It has a VERY firm shift, and I like it alot! Makes quite a difference compared to the old one.

Future plans are going to include a 2" lift and 33's, and since I might have just found a set of 3/4 ton axles with 4.10's maybe an axle swap.

Thanks for the replies!
 

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