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Fluid Change Recommendations.

L.A.X

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City, State
Los Angeles, Ca
Year, Model & Trim Level
1991 Ford Explorer EB
I am going to change the transfer case, front and rear differential, transmission and motor oil this weekend. Do any of you have any recommendations on a specific brand or type of oil/fluid for a 1991 Ford Explorer EB 4x4 with 270,000 miles?
 



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Motor oil: You may get some arguments on this one but here goes anyway.
Mobile 1 Full synthetic 5W/30 just as recommended. I say; do not fool with the viscosity on this one. Use 5W/30.

Limited Slip rear = SYNTHETIC ONLY. Royal Purple 75W 140. Not cheap but there is no substitute!

Open diff's SAE 80W/90

Transfer = Mercon V ATF

Auto trans = Mercon V ONLY! ... ..Not Mercon with additives equivalent to Mercon V. Or Dex/Merc (Label must read Mercon V)

Personally I've been using Valvoline (only one I found with Mercon V on the self)

Transmission has actually improved over the last 4 years. Not so much trouble with the morning sickness and overall better shifting and definitely smoother TCC (no more chatter/vibration at HWY speed)

Standard trans: Mitsubishi = SAE 80 EP gear oil.
.....................: Mazda = Mercon V

Since you have a 91' you are going to have to verify which manual trans. (if it is manual)

These are factory specs, not an opinion BTW (except for the brand names)
 






I have an automatic transmission. How do I know if I have a limited slip diff? I know that I have 3.73 gears in the back. So for the viscosity, the recommendation is 5w/30? How much does the Royal Purple run for?
 






I have an automatic transmission. How do I know if I have a limited slip diff? I know that I have 3.73 gears in the back. So for the viscosity, the recommendation is 5w/30? How much does the Royal Purple run for?

It's an EB so probably does. The tag on the diff will read L3S73.

LS for Limited slip 373 is the ratio.

Yep, the Engine calls for 5W/30 for all weather conditions. Tiny oil hole in the rockers likes the thin stuff. I think this is where people have contributed to premature rocker arm wear.

My valve train is quite as a church mouse at 140,000.

The Royal Purple IIRC is $35 a quart, so it's a $70 fill-up. Hooks up the LS real good, burn'em both on the asphalt.

Worth it though. When I bought my Ex it had gear oil in the LS; clutches where gone, ring and pinion hummed like a freight train, bearings were shot, total loss. Swapped in a 98' LS with disk brakes.
 






270K Almost to the 300 club!
 






When I first bought mine I ran High detergent synthetic blend in the motor for three 1000 mile runs to clean out any sludge, plus I had no idea what was in there.

Sort of weened it off the natural oil then I went to the Mobile 1.

Runs clean from change to change with no usage.
 






Is it ok to put 75w 140 in an open rear end?
 












I'm cheap, so I always use Valvoline Synthetic gear oil in 75-90. Never had a problem with gears, lockers, limited slip, etc. It was recommended by a few people who make a living off of drivelines.
Transmission and transfer case I always have run Mobile One full synthetic. Runs much cooler with synthetic. Since you don't have to change out the transmission / transfer case fluid very often, its worth the money.
Engine oil, I just get whatever is cheaper brand name 5w-30. Change it every 3000 miles, or yearly, whichever is first (usually ends up being yearly). That reminds me, I have changed out all the fluids recently, except for the engine oil.
If you are able, drop a small, powerful magnet in the recess in the bottom of the 8.8 housing, or the diff cover. Cheap monitoring device.
 






5w-30? Hmm....we've always used 10w-30. Sticker on my XLT even says 10w-30...
 






Have any of you used Walmart SuperTech auto transmission fluid?

I have reports that it is as good or better than others!
 






I would NEVER use Walmart brand or anything from Walmart for inside my engine (or outside of it for that matter.) The reason their prices are cheaper is because their products are cheaper...if you look at their tires (Goodyear Wrangler Radials for example,) they might be cheaper at Walmart, but they also have less tread and wear out a LOT quicker due to lack of quality (trust me....found out the hard way........)

But that's just my opinion...take it as you will! :)
 






Mercon V vs. Dex/Merc

I think it would be interesting to hear from owners who HAVE ACTUALLY USED Mercon V and/or Dex/Merc fluid in their A4LD transmissions since Mercon is no longer made.
It seems that there are a lot of OPINIONS but not necessarily EXPERIENCE.
Brand names would also be useful.
No offense is intended toward anyone, I'm still just a little confused on the issue.
THANKS.
Tom. :D
 






I use Wix Oil filters exclusivly which for the 1st gen is a 51515. I buy them buy the case so I pay about $3.50 each for them. I also use them as the external transmission filter on both the Explorer and the Tow rig.. I change the one for the transmission every time I change the one for the engine..

As for fluid.. All of our vehicles except the Van (460 ci) get either mobile 1 synthetic or Mag 1 synthetic. I figure we are doing something right as the Explorer motor went 355k miles before I rebuilt it and the 2006 mustang is at just over 250k miles and the 2000 civic is over 260k miles.. I change the oil about every 6k-9k miles.. The explorer oil is changed once a year now since I put < 6k miles on it a year now.

The diffs have always gotten mobile 1 sythetic. I can't say it is worth the money or not.. The Mustang developed pinion noise somewhere before 200k. I fixed it by replacing the 7.5 with an 8.8 axle.. The Explorer diff was rebuild at 180k miles and I'm showing some wear on the ring gear now at 390k miles....

For transmission, well, I never had good luck with the a4ld so I'll let others speak on that..

~Mark
 






We've always used NAPA brand fluids or CASE brand. In case you're wondering; yeah, like the tractors....dad is a CASE IH mechanic so we get fluids and batteries cheaper through them.....

I still run NAPA 10w-30 for engine and NAPA Gold or NAPA Platinum filters. When I pulled the transmission from the 93 to put in the XLT, I switched the fluid to Amsoil 80w-90 (apparently dad had been using ATF in our M5OD...said that's what it called for...not sure where he got that idea.) I haven't heard anything but good things about Amsoil, and I've already noticed improvements in the way that the tranny handles itself, so once I do my axle swaps I'll probably be going with Amsoil's Severe Gear 75w-140 for the diffs.
 






Thanks everyone
 






Good luck with A4LD

I use Wix Oil filters exclusivly which for the 1st gen is a 51515. I buy them buy the case so I pay about $3.50 each for them. I also use them as the external transmission filter on both the Explorer and the Tow rig.. I change the one for the transmission every time I change the one for the engine..

As for fluid.. All of our vehicles except the Van (460 ci) get either mobile 1 synthetic or Mag 1 synthetic. I figure we are doing something right as the Explorer motor went 355k miles before I rebuilt it and the 2006 mustang is at just over 250k miles and the 2000 civic is over 260k miles.. I change the oil about every 6k-9k miles.. The explorer oil is changed once a year now since I put < 6k miles on it a year now.

The diffs have always gotten mobile 1 sythetic. I can't say it is worth the money or not.. The Mustang developed pinion noise somewhere before 200k. I fixed it by replacing the 7.5 with an 8.8 axle.. The Explorer diff was rebuild at 180k miles and I'm showing some wear on the ring gear now at 390k miles....

For transmission, well, I never had good luck with the a4ld so I'll let others speak on that..

~Mark

We seem to have a lot of people speaking on the a4ld, and that is what I am primarily interested in since I have one in my recently acquired 1991 Ranger.
I would still like to hear from some of them about their own EXPERIENCE with Mercon V and Dex/Merc. Pros and cons about each.
Thanks,
Tom.
 






There's no pro's and con's here;

If you put anything other than Mercon V in a a4ld you will kill it.

The friction material used for the clutches require the specific friction modifiers in Mercon V.

There is no proper substitute on the market.
 






Castrol Mercon V

Is anyone using CASTROL TRANSMAX MERCON V?
 



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