Sorry if this has been asked before, but I searched for an hour and haven't found a similar post.

2002 F150. The manual recommends 75W-140. Is 75W-90 AMSOIL an acceptable replacement? The service center at my local dealership says no, but he has to I assume since Ford specifically mentions 75W-140.

Thanks.

 

Go with the 75-140, it used to be fairly Ford specific and $20 per quart but now it's everywhere. Make sure it's synthetic and add the friction modifier if you have a limited slip. There are other friction modifiers out there as well but I'd stick with Motorcraft at $3-4 a bottle.

 

I believe Amsoil has a 75-140 weight available...

EDIT: here is a link

Amsoil 75-140 gear lube

Matt

 

What would be some differences between the 2?

AMSOIL says that 75W-90 is recommended for most applications. Both the 75W-90 and 140 offer GL-5 protection. They also say that fuel economy is better on the 75W-90. According to their website it 75W-90 is fine for all but the most demanding conditions. The most demanding that I get is driving on sand or towing a bass boat with a weight under 3500 lbs.

Not trying to intentionally go against the Ford recommendation, but I already have a bunch of the 75W-90 and if it is fine and will not cause harm then I would like to use it up. I am also not opposed to going to the recommended weight if the lighter weight is taking a gamble.

Thanks.

 

I opted to be safe and went with the Valvoline 75W-140 for a whooping $15/quart at Advance! Jesus that stuff is more expensive than your AMSOIL and Royal Purple, but at least I didn't have to wait for shipping.

Thanks.

 

I think that was a good decision...I am not an oil guy, but I think I remember reading somewhere the logic for the 75-140 weight...haven't been able to recall since this thread started, but if I find it, I'll post up.

Matt

 

I used 75W-90 Royal Purple when I did my gear swap. It works fine.

 

Walmart has the 75w140 synthetic now for less that $9/qt.

 

Dear mstaszew Wal Mart sells the 70-140 synethic gear lube for $7 a bottle, and NAPA sells this little pump thing that u can screw on any bottle of gear lube for $5, its really neat , it has a long hose and u can pump it in without making a mess.

 

Wise move. There's a thread somewhere in here that talks about how hot these diff's get. That's why Ford runs 75w-140 in 'em. Next time you go to change it, put a Mag Hytec cover on. Increased capacity, aluminum, o-ring sealed, finned for cooling, dipstick, drain plug. It's pricey, but so is a rear.

SL

 

Wow. Those mag-hytec covers look bas-a$$

I'm not sure that I will drop the $240.00 for one though since I just do normal street driving, tow a bass boat, and drive on sand. Nothing too extreme.