Submerged Axles on 2005 F350

I've been in water above the centerline of the axles on my '02 F350 several times. Haven't had an issue thus far, but I've followed Ford's maintenance schedule to the letter in my 67,000 miles. I haven't purchased Ford brand oil tho. I don't recall the brand off hand, (probably Mobil1 'cuz that's what I've used in the engine since the 1st change) but it met all the Ford specs and had the proper friction modifiers for the limited slip diff. I provided the oil to my mech and let him change it out. (easier for him to deal with the mess and he only zinged me $20 for both axles)

On my 2005 F350 with the Ford 10.5" rear end, the synthetic gear oil apparently never needs changing unless the axle has been 'submerged'. The front diff falls under another schedule. It gets swapped at 150K miles unless the axle has been 'submerged'. If you do extreme duty or you have Dana's everything changes.

Rod,

If ya wanna play, ya gotta pay! :-) You have to change the gear lube in both of your axel assembles. Oil seals are NOT water tight. With no drain plug you have to pull the cover (or if you don't have a cover, pull both axels and the 3rd member).

Changing the gear oil is a whole lot easier and less expensive than rebuilding or replacing your axel assembles. DO NOT switch to a non synthetic oil, you are driving a $35,000+ truck why scrimp on $60 dollars worth of synthetic oil???

Good Luck

SYN or not, 150k is to long for lube in a rear axle in a truck as it picks up contaminants and wear particals and there is no filtering system. Any lube gets dirty. On being under water, simple pull fill plug on diff when warm after a trip and look for presence of foaming in lube or a bit of milkyness to it. If it has theses then it has water in it and should be changed. A much bigger concern in the front axle hubs and bearing as they are not vented and when they are warm and then fully submerged they can sometime pull some water in past seals for a partail vacum formed for rapid cooling in water of hot hub. If you run in water a lot you need to teardown and insept the condition of fron hubs on a Ford or old truck that has a solid front axle with lockout hubs too.

Thanks for the replies. Now all I need is a ream of gaskets and two barrels of gear oil. Why not switch to a non synthetic oil? It seems like an alternative if it is replaced regularly

This a waste of money (using syn) because syn gear oil gets dirty and wet just as easy as dino oil and you can change axle oil 3 or 4 time for the price of one syn change and frequent changes is what keeps axles and gear cases alive in harsh environemnts, not they type of oil you use. In a engine it is dbateable because it is filtered but in a closed axle or gear case it need to be changed regularly if you want long service life in harsh conditions.

Napa sells "Right Stuff" gasket material. Like rtv, but not/ 15.00 a can but well worth it. Most rear ends don't use any paper gaskets, just the spread on type.

Wasted money as old dino gear oil (properly graded for use) will do just fine and I have never lost or wore out a properly sized rear axle using it. It is a myth that you need syn gear oil for your 35k + truck to last. The rest of the truck will give up long beter the diff’s do when you use dino oil in them. I have a 79 J20 jeep that has never had syn oil in diffs and it has had a HARD life haul, plowing snow and pulled stock and grain trailers and it diffs are still tight and quiet. Plus like I said earlier, syn oil get dirty and full of water just as easily as dino oil and it is a lot more economical and viable to change the oil for 8 or 10 buck after running in water than 4 or 5x more because it is these changes that will keep it alive not the use of syn.