8.8 gear oil change

[russ1979]

i just had the rear gears swaped out (put in 3.73's)
the shop that did the job suggested i take it easy for the 1st 500 miles then change the oil in the 8.8.

i plain on taking out the dino oil and putting in royal purple.

but

How many QT's do i need?
and
do i need friction modifier again?

 

[347HO]

To keep your warranty, you probably need to follow your shop's recommended fluid and level plus friction modifiers if required.

 

[MustangLX-5.0]

Yes. always use friction modifier. If you have an 8.8 ... which you do .. and it has Traction Lock (AKA Ford's version of POSI trac) , then you NEED friction modifier. I always add it in my standard 7.5 on my 3.8. It prolongs the gear and seal life. The friction mod is usually in a tiny bottle. Pour the friction modifier in first, then add the gear oil. I always pump oil in there till it starts to dribble out the hole. Then tighten the plug and your set.

They say "Take it easy" because it takes a little time for the gears to seat in properly. If you GET ON IT during this so called break-in period, you're liable to prematurely wear them down and create a rough spot. They are usually pretty tight in place when first installed (just like engine rebuilds).

 

[347HO]

LOL.... so disregard the warranty and put whatever in there?
Who's going to take responsibility if the gears go?