Which Dexron 3 fluid would you choose?...

[Ramblin Fever]

on a '97 Isuzu Rodeo with 4L30-E GM auto transmission?

The theory of this model of transmission is it'll do one good if it is highly maintained/serviced with clean fluid, and never allowed to run low. But can be your worst enemy if neglected.

BTW - this year of GM transmission does not have a dipstick, but rather is a closed unit, but not unserviceable.

This truck has 156k miles, original transmission that sees a lot of heavy/hilly mountain driving (i.e. Continental Divide), occasional towing (not so common anymore), and tires 2 sizes bigger, with mild offroading (rough forest roads), and it's fair share of stop/go city driving.

This tranny shifts as smooth as butter and has been flushed every 30-35k miles, filter and pan dropped twice in the 156k miles.

I have decided, with it's higher mileage that I will not have the flush performed again but rather just do partial drain/refills every 10k or so.

I have NO idea what brand of Dexron III fluid is currently in the transmission, but don't believe it's of importance, as they're all compatible

I do have a very minor, but annoying leak at the floor shifter, but fluid level has not changed in just over 5k miles and 4 months; this seal will be replaced in time.

For now, I want a fluid that's good for seals, but don't necessarily believe

that I need a HM ATF as this transmission is shifting just as good as the day I bought it new, and I do NOT want an ATF with additives or special cleaning ingredients.

Basically, I do not want to cause problems; just want to keep it going as good as now.

I've looked at the Castrol Dex 3; Maxlife ATF, and HM Maxlife ATF - which of these, or other brands do others prefer or recommend?

I'm open to any comments or thoughts, except I do NOT want a synthetic ATF at this stage of the transmissions life, it's done good all this time on regular ATF with no repairs of any kind.

 

[Brett Miller]

Pennzoil is hard to beat.

 

[Ramblin Fever]

quote:

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Originally posted by Brett Miller:
Pennzoil is hard to beat.

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Can you state why? Would like your experiences.

 

[The Critic]

Check for the date of the last transmission flush. If the flush was done after 2004, more than likely, it was performed using the Dexron-III(H) fluid.

If you'll be doing a partial drain/fill so often, I'd be very surprised if you're able to discern significant differences between Dexron-III(H) fluids of the same price range.

SuperTech Dexron-III(H)/Mercon would be my pick, solely because of cost. I see no advantage by using the major brand (i.e. Pennzoil, Chevron, etc) product, again, if you'll be doing a partial service so frequently. Even if you were doing longer drains, I doubt there'll be significant differences either.

Cost is about $6.50/gal.

 

[Ramblin Fever]

Is there a difference between Dex 3 and Dex III (H) fluid?

 

[The Critic]

In short, the main difference between DexronIII(G) and DexronIII(H) is the upgraded base oil needed to attain the "H" designation. With DexronIII(H), Group II or better base oils are now required. The service interval has also been extended to lifetime fill for passenger cars, and 100K for light-trucks/SUVs under normal service, or 50K while towing.

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=16;t=001246

However, at the end of this year, Dexron-VI will replace Dexron-IIIH.

PS- If the transmission flush was last done in 2004, it may or may not have the “H” spec-ed fluid. For sure, if it was flushed in 2005, then it should have Dexron-III(H).