Switching from Synthetic ATF to Natural?

Hello Everyone,

About 2 years ago I rebuilt my 700R4 automatic trans in my '88 Chevy blazer s-10 4x4. As I was completing the job, my brother mentioned to me that I should put Mobile1 ATF in. Unfortunately he had meant natural Mobile1 whereas I bought synthetic. Obviously synth. is much more expensive and not what my 700R4 was really designed to be using. The big question is, can I switch back? If so, is there anything that I need to do other than dropping the pan, draining and a new gasket?

TIA, Joe

Reply to
Joe Webster
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There is no problems and only benefits to running synthetic in the 700! If you really don't want to put synthetic in when you do filter changes or when it gets flushed, then don't. There is nothing special that needs to be done. Synthetics and petrol based ATF are fully compatible with each other. Synthetic is much cleaner and will be much better for your trans in the short AND long term, but its your Truck, your call.

Reply to
Shades

Is there a good 'blend'? Something well suited for the 700R4?

Reply to
GC

The better the trans fluid that you run the farther ahead you will be. I don't know off hand of and ATF blends. If you have synthetic in it, my best suggestion is to run it! It will cost more in the short term but will pay big in the long term and even help with shift quality and cool running for the life of the trans.

Are you due for a filter and flush? Is that why your talking about converting?

Reply to
Shades

Well cost wasn't really my concern. I thought that I would be better to run natural in the 700r4. It would probably cost me $36 for natural, and $60 for synth -- I can afford the $30.

The first reason why I considered switching back was if it were doing harm or being less effective in the 700r4. The second reason is that I noticed that at high RPMs on the highway it will run at (for example) 3500 rpm. After 10 seconds, the rpms drop down by 400-500 rpm and you feel the truck pick up a little bit -- like the trans just clamped down a bit harder on the clutch plates. I thought that the synth was too thin and that it was taking longer to build up pressure on those plates. There is a small drip coming from where the control level runs in through the case -- nothing so much that there is ever a spot on the ground, but enough that I notice it's a little wet around there. That may -- over time cause my trans level to be low. I'll check it again tomorrow and see if that's the case.

Reply to
Joe Webster

Reply to
KENG

70-80 :)
Reply to
Joe Webster

What size tire, what gear ratio, and is that in 4th?

Reply to
Shades

for real, that sounds like alot of rpm to be cruising around

Adair

Reply to
Adair Winter
12x5x9, 7.53, 2nd gear

Seriously though, 29" tires 3.73 in 1:1 (not OD) would be 81MPH at 3,500RPM

GMC Gremlin

Reply to
GMC Gremlin

Use 4th!!!

Reply to
Shades

Well that's not cruising -- I was trying to see if it was slipping/not engaging.

Reply to
Joe Webster

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