Rear axle oil?

[Slimthehippie]

I am new to small diesel engine so any and all help is appreciated. I just bought a 88' f250 single cab 2wd 7.3 idi 195,000 mi for $700. My guess is that the PO was not a diesel guy or even a mechanic. 5 gp were bad, no air filter or air box, cobbled together ignition and lights. So I am trying to breath new life into it. This truck is needed to drive 500+ miles and then sit for a month or more, then another 500 mi +. I have fixed the air filter/air box issue, 5 new Motorcraft gp, 3 more to follow when I get home (I drive OTR semi), headlight relay mod to follow soon. I need to do oil change, fuel filter change, coolant flush, will be adding coolant filter. Since my last trucks axle lost all oil and locked up on the drive from Chicago IL to Madison WI, I feel my most pressing issue is to change rear end oil. What oil do I use to replace old oil.

Very sorry for long winded post.

 

[PwrSmoke]

Depends on what you will do with the truck. If you tow heavy or a lot, a 75W140 synthetic is optimal. Brand is fairly unimportant if it's a name brand. They are all "good." If it's going to live an relatively easy life, short term heavy towing and no maximum loads long term, then a 75W90 syn will offer a little better mpg day to day. I think the synthetics are worth the money, especially up there in the "frozen North" of Wisconsin. I believe the speced oils were 85W90 but that oil is like honey near freezing and you may as well benefit from the modern technology! Synthetic gear oil is pretty much an off the shelf purchase these days... no need to find the boutiques. Walmart here recently had a sale on Valvoline synthetic gear oil.

 

[Slimthehippie]

This truck will mostly have an easy life, no towing except a 16' boat a few times a year and mpg is the goal.

 

[madpogue]

Hey, welcome to OBN, you're right up the Interstate from me. Buddy of mine used to live up in Pardeeville doing animal rescue. Portage rocks simply because it has a Tractor Supply . Anyway, the other good thing about the synthetic 75w140 (someone correct me if I'm wrong) is that it works equally well in open or LS diffs, without any additive.

 

[typ4]

Synthetic for all the suggested reasons, takes 3 or 3.5 qts IIRC

 

[Slimthehippie]

Thanks for the help. Now if only I can get the truck winterized before the snow starts.

 

[BDCarrillo]

Make sure you take off the vent tube and clean it out. If it gets packed with crud mud daubers it'll pressurize the rear end when it heats up and show you the weakest point in the seals.

The part that holds the rear brake tee can be unscrewed from the axle tube without affecting the brakes, and it's on the passenger side of the diff. I've replaced the 5/16 hose that runs up to the frame rail and put a little breather cap on it for both my sterling equipped trucks.