dereku

Ok good. I was going to say you have some larger issues to figure out...

mn_f150

Question on the rear differential oil to use. The owners manual says to use 75W-140 for the rear differential. However, I just talked to a Ford Service shop rep that "I trust" and Ford recommends putting in a 80W-90 instead. They have seen issues with bearings going out in the rear end for trucks that drive high speed miles (70 mph) speeds with a load, and their Ford Rep has indicated that the oil should be 80W-90 vs. the 75W-140 in the owners manual. Since they have switched, they have not seen the problem since.

So, should I go with 75W-140 or 80W-90 in the rear differential? Any words of wisdom here?

dereku

It is thinner when cold and slightly thicker when warm so it shouldnt cause issues. And if a ford rep says thats what they do i would try it.

mn_f150

Quick update (for everyone that helped me with critical information.)

I ran Techron PEA fuel system cleaner for 3 weeks (4 bottles worth.) I prepped the plugs on Thursday night with solvent and let them sit over night. Friday morning I tackled the task of taking out the plugs manually (no air tools). Well, I ended up breaking 5 of the 8 plugs, with having the honor of having the back two plugs break.

The plugs that broke in front; not too bad. You could get leverage on the Lisle tool. Yikes, what a task on the back plugs. I struggled to get enough pressure on the Lisle tool to get them out, but ended up using a small hammer to tap the tool to get it started. I started at approximately 9 a.m. and finished up at 3:30 or so. For a few hours, I thought I was stuck on the back two plugs and would have to call a mechanic, but it eventually worked out.

I used Motorcraft sp-515 plugs with Nickel anti-sieze component. Did I hear someone say that this problem won't occur again when I change these plugs out again in 60,000 - 80,000 miles?

Thanks all for the advice; now will tackle the front and rear differential fluid and the fuel pump module in the back end.......

mn_f150

I changed out the rear differential fluid at 79,000 miles. I was quite surprised at the amount of metal filings clinging to the magnet on the fill plug. Must have been 3/16" thick.

The old fluid is a dark gray color and the new is clear. So yikes, definitely overdue. (I would attach pictures, but need to research how to do so.)

Anyone have trouble getting their front differential cover off? I started this job but was stymied by 1 bolt that was too close to a metal tube. May have to bring it to the shop for this one..... Any pointers?

Thanks,

mn_f150