I have searched several different ways for discussions on the differences in PM Schedule A and B, but they all came up empty. This had to be discussed at some point, or maybe I am the first to actually ask about it....

Schedule A says nothing about the front or rear axles, just the Transfer case at 75K miles.

Schedule B says front and rear axles every 12K miles and the transfer case every 36K miles.


I haven't scanned every line item for other differences, just focused on these.

I'd like to hear some logic as to why we may never change axle fluid If we're always driving more than 5 miles per trip and rarely above 90° F outside temp. Then, it seems changing axle fluids every 12K miles is going overboard in comparison. I guess I have to take the other things into account as well, dusty, towing a lot, etc.

Is the dusty conditions assuming we're in 4X4? if never (hardly ever) in 4X4, then there is no wear on the front diff and rarely a need to replace fluid.... if I use the schedule A mentality.

Guys, I'm just trying to learn and make sense of it all. Rather than doing it because that's how it's always been done (5 monkeys, if you know the story).

Thanks again,
Robb

 

I would just say change out the diff oil every 3 years and top it off or check it every year unless you drive like a maniac or 4X4 then more often

 

I don't think there's a magic number on axle fluids- Motor oil has a known half-life plus you change it due to contamination [fuel/water], transmission fluid/hydraulic fluid has a known half-life plus you change it due to contamination [clutch material], transfer cases and manual gearboxes, the fluid has a half-life, but doesn't really get contaminated unless you have a bearing on it's way out or you're chewing up gears. Axles are the same way typically [key word], but will get contaminated if you 4WD alot and dirt/water/muck gets past the seals.

 

Even in 2WD, eveything in the front axle is moving. It may not be under any load, but I'd still change the oil once in a while.

 

It all depends on what your truck goes though. City(stop and go, hot temps)
Then that should be under the severe(I think is was silver that says he does 12k for what his truck goes through) If you live where I live it rarely gets above 80 and stop and go traffic for hrs isnt happening. If you off road a lot or do a lot of water crossings. I would check it often to make sure it doesnt have water or mud in it. The 12-15k would be a good change interval. Like my truck Im never in stop and go,temps are never that hot,I dont off road a lot, towing is maybe once a month. I haul more times a year then I tow. So Im doing mine at 30k. Which will be like every 2 years lol

 

Thanks for the input.

It'll be subjective as to what I put the truck through. I doubt I did anything wrong to cause wear on the axles or pinion, just 200K miles..... and my recent off-road fun in the mud, muck and deep-water near-death experience.

Appreciate y'all!