What rear diff fluid for 1990 ranger

[Skimbletonkydungledonkey]

Hi i have a 1990 ranger xlt. I believe but want to confirm mercon 5 rated fluid is the correct one fir the trans. But for the rear diff im unsure of the oil weight required. If anyone could help that woukd be great. Also if anyone has experience is the automatic transmission easybto remove from these trucks? From a quick look under it doesn't look too complicated i just want to make sure there isnt a specific thing i should look our for when removing it. Its got a leak probably from a seal and I'll need to drop it before long to get new seals installed

 

[Dirtman]

Well skimbletonkydungledonkey... the answer is 42.

 

[alwaysFlOoReD]

Well skimbletonkydungledonkey... the answer is 42.

Nope....the answer has changed since we're in a new millennium.

As far as the OP question, I've never had any problem using 80w90 in all my old trucks. I believe the newest Ford's use 75w140 synthetic, but that's not going to happen with my wallet.
I just picked up a 5 gallon pail of (IIRC) gl5 which is spec'ed for all the rear ends I service....

Shut up dirtman....I'm talking automotive booty.

 

[sgtsandman]

Yep, 80W90 or 75W140. Ford says the synthetic is for the life of the vehicle but never specified what they think “life” is. You didn’t say if your truck is RWD of 4X4. The rear axle recommendation is 100,000 miles for fluid changes and the front is 150,000. Personally, I would recommend every 30,000. The same for the transmission fluid. But I wouldn’t go more than 60,000, especially with the transmission. Not unless you like giving transmission shops your money for replacement transmissions.

 

[Skimbletonkydungledonkey]

Alright thank you all. Ill probably just put some cheaper stuff in for now till I get all the other kinks worked out. I try fo be liberal with my fluid change intervals usually too. Unfortunately tranny is leaking from a seal likely so while im under there to drop the tranny im gonna check out the rear diff

 

[19Walt93]

Look on the dipstick for the transmission fluid spec, I think Mercon was still used in 90 and Mercon V came later.

 

[Dirtman]

Mercon V is backwards compatible with mercon in everything but some transfer cases. I got bored one night and read all the stupidity involving mercon vs mercon v vs xl12 (transfer case fluid). Long stupid nonsense but bottom line, if it took mercon it can take mercon v (transmissions, power steering systems and most transfer cases) NOT certain t cases that originally required original mercon and now need xl12 (only applies to cases with a clutch).

Its essentially just licensing and branding crap. Mercon technically no longer exists.

 

[19Walt93]

Mercon V shouldn't be used in transfer cases, the new xl 12 t case fluid meets the old Mercon spec but costs a lot more. Napa, Valvoline, etc still sell Mercon at more reasonable prices. Ford's "power steering" fluid is also Mercon spec, not Mercon V, again for more money than other brand Mercon fluid. Some Ford trans techs used to say in the FMCDealer message boards that they thought Mercon V was better fluid than the later Mercon LV. I don't know about that but the LV fluid certainly stinks and turns dark very quickly.