Best Dexron for filling M5R1 and BW1350 manual case?

Natedog · Oct 6, 2007

Just got my rebuilt M5R1 tranny back last night. I've read that Valvoline meets many specs like Allison, Caterpillar TO2 (hydraulic pumps), etc. Castrol has been a great motor oil for me. I don't usually run synthetic because of the cost, but want my tranny and transfer to last. I do run synthetic grease in my u-joints because that has proven its worth in my rock crawler, joints last alot longer! My tranny guy said to fill the tranny and then add about another half quart as he thinks they were not designed to hold quite enough fluid. Pull the fill plug, and shifter, fill the tranny by pouring Dexron in through the shiffter hole until it runs out the fill hole, install filler plug, and then pour about another half quart in. Soooo.....

What is the best Dexron for filling M5R1 and BW1350 manual case? Regular petroleum based, synthetic, or? Any brand that you think is better than another?

Simple_serf · Oct 6, 2007

The fluid ford says to use if mercon or now mercon V

Dex is GM spec I think.

I wouldn't bother adding more fluid...When mine was overfilled, it puked fluid out of the rear seal. I have found that mine isn't as notchy between 2nd and 3rd when I use Motorcraft. It was a little bit so when I used Castrol, and it really was bad when I used some multi vehicle crap.

It has 187K on it and it still hasn't blown up yet.

Sasquatch_Ryda · Oct 6, 2007

Mercon or mercon V is what you're wanting for that tranny. Overfilling is never a good idea, if it needed more fluid, they would have designed them that way.

4x4junkie · Oct 6, 2007

I've been using Castrol "DextronIII/Mercon" ATF with no complaints.

Natedog · Oct 7, 2007

Yes Dexron is usually for GM, but my Toyota calls for it. How much is the Motorcraft Mercon? Nobody has tried synthetic?

racsan · Oct 7, 2007

ive had mobil 1 syn in for about a year, it works, no better-no worse than any other atf ive had in it. ive heard some chat about pennzoil syncromesh fluid. but then again once i thought it was a better idea to run 80w90 in a jeep cj-7 trans that was supposed to have atf in it. was a bad idea. noisy in the spring and hard to shift in winter. i'll just live with my trans occasional weirdness and innability to downshift at certian times (got to rev a little between downshifts on 5-4 and 3-2 while clutch is still pushed in.) i change fluid about once a year so iguess im about due again.
________
jugalettes

AllanD · Oct 7, 2007

synthetic doesn't make a trans or t-case last longer

Actually CHANGING the oil accomplishes that.

I recommend AGAINST using Mercon5 in a Mazda manual Trans,
but think it's OK in the T-case, I run Mercon5 in my T-case
but there are "shift quality issues" with Mercon5 in the manual trans,
so I run Mercon3 in my trans.

I use Motorcraft fluid in both.

AD

Simple_serf · Oct 9, 2007

Where do you get it?

I looked for the plain Mercon that I used to use with good results and I couldn't find it, even the Ford dealer only had Merc V. The newer m5od spec in their book is for the merc v.

Had to dump that in my PS pump too, for the same reason.

I heard some bad stuff about merc v as well, but I didn't really have a whole lot of choice, and I figured it HAD to be better than the crap the *&@#ing shop put in it in seattle (Multi vehicle...that's all the can said)

4x4RangerGuy · Oct 9, 2007

Mercon V is a just a slightly thicker version of Mercon that they call for in the newer series automatics. It theoretically meets Mercon specs as well, but it is just slightly thicker.

Mercon is sold usually as Dexron III/Mercon in most auto parts stores. Mercon V wouldn't hurt your trans, but I would follow AllanD's advice and just use DexIII/Mercon in the trans. Mercon V in anything else should be fine.

I run DexIII/Mercon in my tranny and tcase as well as my PS pump. No problems here.

Sasquatch_Ryda · Oct 10, 2007

Ford has discontinued the use of regular old Mercon, and have switched everything up to MerconV. As far as i know merconV is semi synthetic and mercon sp if full synthetic.

exbass94 · Oct 10, 2007

Sasquatch_Ryda said:
Ford has discontinued the use of regular old Mercon, and have switched everything up to MerconV. As far as i know merconV is semi synthetic and mercon sp if full synthetic.

You can still buy the Napa (Valvoline) brand Dex III/Mercon at Napa stores. The store I work at stocks a ton of it. We also sell Valvoline (not Napa brand) Mercon V full synthetic.

AllanD · Oct 10, 2007

If you have a new enough Ranger ford made internal changes to the trans, primarily using composite synchro rings that use carbon fiber friction material on the inside of the synchro rings that are specifically made for use with the Mercon5 fluid.

My problem wiht shift quality was with my last trans, not my current one.
MY current one was built almost entirely with 2003 internal parts, so yeah, it has the carbon faced synchros, but when the time came to fill it I just couldn't make myself
pour Merc5 into it because of my prior experience.

BTW, MErcon5 is full synthetic MerconSP is COMPLETELY different and NOT intended
for use in parts where Mercon5 is specified.

AD

Natedog · Oct 23, 2007

Picked up some Valvoline DexronIII/Mercon yesterday....reading all the bottles it seems to be the same as MerconIII. Not going synthetic, too much $$$ and yes changing the fluid does alot for parts life. TOo many people never change it and don't understand why thier tranny wore out.

Best Dexron for filling M5R1 and BW1350 manual case?

New Member

New Member

Well-Known Member

Forum Staff Member

New Member

Well-Known Member

TRS Technical Staff

New Member

New Member

Well-Known Member

Well-Known Member

TRS Technical Staff

New Member

Sponsored Ad

Sponsored Ad

Member & Vendor Upgrades

Truck of The Month

Recently Featured

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store

Sponsored Ad

Sponsored Ad

Sponsored Ad

Amazon Deals