hi,i just bought a 1999 f150 lariat5.4,trlr. tow.pkg.,l/s,355 rear,&all the other inc. goodies.i tow (occasionally)a small 5th wheel(3800 lbs)which i bearly feel,should i replace my auto tran.fluid w/synthetic fluid?my first service is coming up,3000miles.it looks like it would take 15/16 qts to do everything.also has any one put a trans temp gauge? thanks pat

 

Pat,

Your trans is equipped with synthetic fluid from the factory (Mercon IV) as marked on the dipstick. Read your owner's manual.....

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Dunbarton "The Middle Aged Kid" '99 XLT SC SB 4x2 4.6 auto 3.55 ls The occasional Z-71 Eater! Wedgewood & Denim, SuperChipped, Airaid FIPK, Rhino Liner, leaky rear slider. Man, I got it all!

 

dunbarton,thank you for your response,however my transmission has just plain old mercon in it.mercon V is synthetic not mercon,parts guy said that non synthetic is also known as mercon III(3).in trying to get to a mechanic(technician),i was told that to put synthetic in, every drop of non-synthetic must be drained.another service rep said, what you have is good enough!this is kinda like the x-files,the truth lies somewhere out there! pat

 

Pat - my Owner's Manual states that my transmission is filled with Synthetic Fluid.
I have a 250 Super Duty. Maybe the Light Duty trucks don't come with Synthetic.
My .02

 

my 99 F150xlt ,5.4,3.55LS,tow pkg,came from the factory with synthetic Mercon V in the trans and synthetic oil in the differential.
Dipstick on trans is marked Mercon V and
owners manual specifies synthetic in both trans and diff.

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I guess they all have synthetic fluids.
Now that I've changed my oil to Mobil One, I've got synthetic everywhere

Live better chemically...

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1999 F-250 XLT Super Duty Crew Cab Long Bed
V-10, Automatic 4R100, 4.30 Limited Slip.
GVW = 6700# Towing Capacity = 13,300#
4 Wheel ABS disks + Reese 15K hitch
Dark Hunter Green. Ford Running Boards.
Grey Rhino-Liner. Captain's Chairs. CD+Tape
Polished Stainless Steel Wheel-well Molding http://members.home.net/jchartier/jnctrk.html

 

with hat in hand,head bowed,tear in my eye,i apoligize, all of you are right.i do have synthetic mercon V.i guess i was totally blinded in figuring how to get synthetic.sorry again,one of the tremendous benefits of a site like this is the expertise at hand! thanks pat

 

Pat,

That's OK, I pulled a couple of "boneheads" here much worse than what you did ...... and I won't tell you where they are either!

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Dunbarton "The Middle Aged Kid" '99 XLT SC SB 4x2 4.6 auto 3.55 ls The occasional Z-71 Eater! Wedgewood & Denim, SuperChipped, Airaid FIPK, Rhino Liner, leaky rear slider. Man, I got it all! (New Jersey)

 

Aw c'mon Dun----. All is forgiven.

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Ben Mc.----'99 XLT 5.4 SC SB ORP Dk. Red/Dk. Grey----Fact. Cab Steps/Tonneau/Slider----Straight Duals, Superchip, Airaid/KN (non-sag), Ungo Autostart/Keyless Remote, Prime Designs Air/Bug Deflector, Weathertech Wind/Rain Deflecters----PPI 4240 Amp,McIntosh 6x9's w/crossovers front, Polk DB 5.25's rear---Tuessssdayyyy Affffternoooooon----gotta love it!